Please help will give brainy points

Two planes leave an airport at the same time, one flying east, the other flying west. the eastbound plane travels 20 mph slower. they are 1600 mi apart after 2 hr. find the speed of each plane.

Solve 2x+y=3 x+y=5 in substitution method

Which shows the correct substitution of the values a,b and c from the equation 1=-2x+3x^2+1