Answer
35 mph and 75 mph
Work Step by Step
car 1: 70 = r*t
car 2: 300 = (r+40)*2t
$70=r*t$
$70/r = r*t/r$
$70/r =t$
$300 = (r+40)*2t$
$300/2*(r+40) = (r+40)*2t/(r+40)*2$
$150/(r+40) = t$
$70/r = 150/(r+40)$
$150*r = 70*(r+40)$
$150r = 70r+2800$
$80r = 2800$
$80r/80 = 2800/80$
$r = 35$
$r+40$
$35+40$
$75$
