每日一题

Mathematics>Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

If a, b, and c are numbers such that a/b = 3 and b/c = 7, then (a+b)/(b+c) is equal to which of the following?

(A) 7/2
(B) 7/8
(C) 3/7
(D) 1/7
(E) 21

答案和解析

答案：A

解析：

From a/b = 3 is implied that (a+b)/b = 4 (1)

And from b/c = 7 is implied that b/(b+c) = 7/8 (2)

If we multiply (1) and (2) together, we have that (a+b)/(b+c) = 4*(7/8) = 7/2 (b is canceled out).