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travels 20 mph is t and the time the car travels 60 mph is T . Then from the formula Rate x Time = Distance, 20 x t = D and 60 x T = D . This gives you t = D /20 and T = D /60. So the total time is t + T = D /20 + D /60. This is equal to t + T = 80 D /1,200 = D /15. So the average rate = 2 D /( t + T ) = 2 D /( D /15) = 30.
    4.     (b) succeeding
    PRE means before; CURS means to run. So, PRECURSORY means to run (or go) before. The opposite is running or going after, or “succeeding.”
    5.     The label BC only could have come into usage after 0 BC.
    6.     Thirteen nickels, one dime, and one quarter
    The cleverest way to solve this problem is to try to reduce the number of possibilities to a minimum and then figure out all of those possibilities. The highest number of quarters I can have is three, since if I have at least one of every coin, I can’t have four quarters (and I can’t have more than four quarters because the total would be more than $1). So, if I have three quarters, I am left with fourteen dimes/nickels, which must add up to 25 cents. That’s impossible, so suppose I have two quarters. That leaves 50 cents for the dimes/nickels. I can’t get fourteen dimes/nickels that add up to 50 cents. So, try one quarter. I have 75 cents left. I can get thirteen nickels and one dime to total 75 cents.
    There is also an algebraic way of solving this problem:
    Let’s say I have n nickels, d dimes, and q quarters. The total number of coins can be represented as:
    (Equation 1) n + d + q = 15.
    The value of all the coins is:
    (Equation 2) 5 n + 10 d + 25 q = 100, since a nickel is worth 5 cents, a dime is worth 10 cents, and a quarter is worth 25 cents.
    Let’s divide the second equation by 5. We get:
    (Equation 3) n + 2 d + 5 q = 20
    Multiply Equation 1 by two:
    (Equation 4) 2 n + 2 d + 2 q = 30
    Subtract Equation 3 from Equation 4. We get:
    (Equation 5) n - 3q = 10
    Now, because of Equation 2, q must be either 1, 2, 3, or 4 and not more than 4, since n and d must be both positive numbers.
    We know from Equation 1 that n must be less than 15, since d + q must be positive numbers.
    If q = 4, Equation 5 tells us n = 22, which is impossible.
    If q = 3, n = 19, which is impossible.
    If q = 2, n = 16, which is impossible.
    Therefore, q = 1, which makes n = 13 and d = 1.
    Therefore, I have thirteen nickels, one dime, and one quarter.
    7.     He could type “The file will be deleted.”
    Think of a statement that will be in conflict with what is mentioned. If the user types “The file will be deleted” and the statement is true, the file’s name will change but not be deleted. Thus the statement “The file is deleted” cannot be true. So it is false. But if the statement “The file will be deleted” is false, according to what is mentioned in the question, the file will be deleted, making the user’s statement true, which would be contradictory. So if the user types “The file will be deleted,” the computer will not be able to perform a function with the file and probably shut down.
    8.     Terry is 5 years old.
    Translate words to math. “Alice was five years older than Terry is now” translates to a = 5 + T, where a is the age that Alice was.
    Now translate again. Terry is half as old as Alice was: T = (1/2) a. Substitute for a:
    T = (1/2)(5 + T ).
    2 T = 5 + T,
    T = 5.
    So, Terry is 5 years old.
    9.     Choices (d) negative : positive and (e) disordered : ordered are correct.
    An imaginary number is a number such that when multiplied by itself it becomes a negative number. However, there is no way a real number multiplied by itself will give you a negative number. Thus, the term imaginary. For example, two times an imaginary number cannot be thought of as greater or less than three times the number. Therefore they are called “not ordered.” The real numbers are ordered. For example, three times the number 25 is greater than two times the number 25.
    10.   355 x 356 is greater