What is the systems of equations?

Question

A northbound train and a southbound train meet each other on parallel tracks heading in opposite directions. The northbound train travels 12 miles per hour faster than the southbound train. After 2.5 hours, they are 300 miles apart. At what speeds are the two trains traveling?

Answer 1

N = 12 + S

300/2.5 = 120 mph

distance = speed time time

d = rt

d/t = r

2.5(N+S)= 300

2.5(12+S+S) =300

12 + 2S = 120

2S = 120-12 = 108

S = 108/2 = 54 mph for the South bound train

N= 54+12 = 66 mph for the North bound train

66+54 = 120 mph, the combined speed = 300/2.5