Rate, time, and distance word problems

Question

Kyle went on a bike ride of 90 miles. He realized that if he had gone 12 mph faster, he would have arrived 10 hours sooner. How fast did he actually ride?

Answer 1

d = rt

distance = rate of speed times time

90 = rt, t=90/r

90= (12+r)(t-10)= (12+r)(90/r -10)

90r= (12+r)(90-10r)