First need to make an equation for each
x = Miles
y = Total Cost
Comp A: 120 + 0.20x = y
Comp B: 40 + 0.60x = y
cancel out the amounts to make it easier (Subtract 40 from each)
Comp A: 80 + 0.20x = y
Comp B: 0.60x = y
insert a problem for y to solve for x
80 + 0.20x = 0.60x
Your answer is 200 miles