Question 952377
r=plane's rate
900 mi/r=250 mi/r-130mph Multiply each side by (r)(r-130 mph)
900 mi(r-130mph)=250 mi(r) Divide each side by 250mi
3.6(r-130mph)=r
3.6r-468mph=r Subtract r from each side.
2.6r-468mph=0 Add 468mph to each side.
2.6r=468mph Divide each side by 2.6.
r=180 mph ANSWER The speed of the plane is 180 mph.
CHECK:
Car's speed=r-130mph=180mph-130mph=50mph
900mi/180 mph=250mi/50mph
5 hours=5 hours