Two planes leave an airport at the same time, one flying east, the other flying west. The eastbound plane travels

Question

Two planes leave an airport at the same time, one flying east, the other flying west. The eastbound plane travels 140 
mph slower. They are 2960 
mi apart after 4 
hr. Find the speed of each plane.

Answer 1

d=rt

r=rate of the westbound plane

r-140=rate of the eastbound plane

d=r*4 (west)

d=(r-140)*4 (east)

4r+4(r-140)=2960

4r+4r-560=2960

8r-560=2960

8r=2960+560

8r=3520

r=3520/8

r=440 mph (speed of westbound plane)

r-140=440-140=300 mph (speed of eastbound plane)

check: 4*440+4*300=2960

           1760+1200=2960

            2960=2960