Question

Sun, a kayaker, paddles 8 miles upstream (against the current) in 2 hours. Returning to her original location, she paddles downstream (with the current) the same distance in 1 hour. The equations represent x, the paddling speed, and y, the speed of the current.

2(x – y) = a
b(x + y) = 8

Which are true? Select two options.

a = 8
b = 8
a = 1
b = 1
a = b

Answer 1

Answers: a = 8 and b = 1.

Reason: Upstream: 8 miles = 2 hours·(x − y) so 2(x − y) = 8 → a = 8. Downstream: 8 miles = 1 hour·(x + y) so 1(x + y) = 8 → b = 1.