[求助]GWD的几道题

Q19:

A total of $60,000 was invested for one year.  But of this amount earned simple annual interest at the rate of x percent per year, and the rest earned simple annual interest at the rate of y percent per year.  If the total interest earned by the $60,000 for that year was $4,080, what is the value of x?

(1)     x = (3/4) y

(2)   The ratio of the amount that earned interest at the rate of x percent per year to the amount that earned interest at the rate of y percent per year was 3 to 2.

An integer greater than 1 that is not prime is called composite.  If the two-digit integer n is greater than 20, is n composite?

(1)     The tens digit of n is a factor of the units digit of n.

(2)     The tens digit of n is 2.

Q17:

If a and b are positive, is (a^-1 + b^-1)^-1 less than (a^-1b^-1)^-1?

(1)     a = 2b

(2)     a + b > 1

Q18:

On a certain transatlantic crossing, 20 percent of a ship’s passengers held round-trip tickets and also took their cars abroad the ship.  If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship, what percent of the ship’s passengers held round-trip tickets?

A.      33 1/3%

B.       40%

C.      50%

D.      60%

E.       66 2/3%

Q20:

A collection of 36 cards consists of 4 sets of 9 cards each.  The 9 cards in each set are numbered 1 through 9.  If one card has been removed from the collection, what is the number on that card?

(1)     The units digit of the sum of the numbers on the remaining 35 cards is 6.

(2)     The sum of the numbers on the remaining 35 cards is 176.

Q32:

What is the remainder when the two digit, positive integer x is divided by 3?

(1)     The sum of the digits of x is 5.

(2)     The remainder when x is divided by 9 is 5.

请教各位NN们^