Question

During rush hour, Bill can drive 60 miles using the side roads in the same time that it takes to travel 30 miles on the freeway. If Bill's rate on the side roads is 7 mi/h faster than his rate on the freeway, find his rate on the side roads.

let bill drive 30 mile (1/2 time unit of sideroads, one time unit on freeway)

Distance are the same
distance sideroad= distance freeway
v*time= (v+ 7)time/2
or divide through by time
v= v/2+3.5
solve for v the speed on the freeway.