Isn't this the sort of math problem we solve in 7th grade?
x1 = 0 + 70*t
x2 = 150 + 20*t
x1 = x2 <=> 70t = 150 + 20t
50t = 150
t = 3 hours
x1 = 70 * 3 = 210km
x2 = 150 + 2*3 = 150 + 60 = 210km
x1 = 0 + 70*t
x2 = 150 + 20*t
x1 = x2 <=> 70t = 150 + 20t
50t = 150
t = 3 hours
x1 = 70 * 3 = 210km
x2 = 150 + 2*3 = 150 + 60 = 210km