Answer
45 mph for motorcycle, 60 mph for car
Work Step by Step
distance = rate * time
car: $600 = (x+15)*t$
motorcycle: $450 = x*t$
$600= (x+15)*t$
$600/(x+15)= (x+15)*t/(x+15)$
$600/(x+15) = t$
$450 = x*t$
$450/x = x*t/x$
$450/x = t$
$600/ (x+15) = 450/x$
$600*x = 450*(x+15)$
$600x = 450x+6750$
$150x= 6750$
$150x/150 = 6750/150$
$x= 45$
$x+15$
$45+15$
$60$
