Question

A bird flies 61/2 mi in 20 min.

How long will it take the bird to fly 81/8 mi at the same speed?

Answer 1

`(61/2)/(20) = (x)/(81/8)`
multiply the 2nd fraction by 8/8 to get rid of the 8 in the denominator:

`(61/2)/(20) = (8x)/(81)`
simplify the 1st fraction by multiplying by 2/2:

`(61)/(40) = (8x)/(81)`
now, you can cross-multiply:

`61*81=40*8x`

`4941=320x`

`x=(4941)/(320)` or
`15 (141)/(320)`