Givens
Slower plane
r = r
t = 2.5 hours
d = d
Faster Plane
r_faster = 1.5 * r
t = 2.5 hours
d1 = d + 127.5
The time is the same for both
t = d/r
d1/r1 = d/r
(d+ 127.5)/1.5r = d/r Multiply each side by r
(d + 127.5)/1.5 = d Multiply both sides by 1.5
d + 127.5 = 1.5d Subtract d from both sides.
127.5 = 1.5d - d
127.5 = 0.5d Divide by 0.5
127.5 / 0.5 = d
255 = d
Now you can go back and figure out the rates.
First find d1
d1 = d + 127.5
d1 = 255 + 127.5
d1 = 382.5
Rate of the slower plane
d = 255
t = 2.5 hours
r = d/t
r = 255/2.5
r = 102 miles per hour.
Faster plane
d1 = 382.5 miles
t = 2.5 hours
r1 = d/t
r1 = 382.5/2.5 = 153 miles per hour.