Question

A tire shop had to fill 2 1 ⁄2 tires with air. It took a small air compressor 2 1 ⁄2 seconds to fill them up. How long would it take to fill 8 tires?

Answer 1

Let 2_1/2 = 5/2.

Let t = time to fill 8 tires

(5/2)/8 = (5/2)/t

8(5/2) = (5/2)t

20 = (5/2)t

20 ÷ 5/2 = t

20 • 2/5 = t

8 seconds = t

Done.