Question

Figure (a) shows a red car and a green car that move toward each other. Figure (b) is a graph of their motion, showing the positions xg0 = 270 m and xr0 = -35 m at time t = 0. The green car has a constant speed of 24 m/s and the red car begins from rest. What is the acceleration magnitude of the red car?

Answer 1

On figure b, a position graph. Where the meet, note the time, and position.

so the distance traveled by carr, is from -35 to the meeting position. So you have time in motion, and distance for car red.
d=vi*t+1/2 a t^2 vi=0, so you can figure a from your distance (from -35 to final position) and time.