Answer
60 mph for motorcycle, 70 mph for car
Work Step by Step
car: 280 = (r+10)*t
motorcycle: 240 = r*t
$280 = (r+10)*t$
$280/(r+10)=(r+10)*t/(r+10)$
$280/(r+10) = t$
$240 = r*t$
$240/r = r*t/r$
$240/r = t$
$280/(r+10) = 240/r$
$240 (r+10) = 280 *r$
$240r + 2400 = 280r$
$2400 = 40r$
$2400/40 = 40r/40$
$60 = r$
$r+10$
$60+10$
$70$