Two planes start from Kansas City at the same time and fly opposite directions, one averaging 55 mph faster than the other. If they are 1796 miles apart after 4 hours, what are their average speeds?

Answer 1

x=55+y

4y + 4(55+y) = 1796

4y + 220 + 4y = 1796

8y = 1796 - 220 = 1576

y = 1576/8 = 197 mph

x = 252 mph

4(197+252) = 4(449) = 1796

time times speed = distance

Answer 2

rate * time = distance

one train rate = x

second train rate = x + 55

time = 4 hours for both

distance = 1796

since traveling in opposite directions rate*time for trains 1 and 2 will add to total distance of 1796.

4x + 4(x+55) = 1796

8x + 220 = 1796

x = 197

x + 55 = 252

check

4 * (197 + 252) = 1796