Question 103764
let x=rate on side roads ... in the same time, he can only go 3/4 as far on the freeway, so the freeway rate is (3/4)x


(3/4)x+7=x ... 7=(1/4)x ... 28=x


using t=d/r ... the times are the same so 40/r=30/(r-7)


cross multiplying gives 40r-280=30r ... 10r=280 ... r=28