physics prob?

Question

Car A and B are traveling in adjacent highway lanes and at t=0 have the positions of car A vel =15km/h and Car B vel=23km/h. knowing that A has a constant accel of .6m/s^2 and B has a constant decel of -.4m/s^2 determine a. when and where A will overtake B. b. the speed of each at that time

Answer 1

part of the question is missing. At t=0 are the cars adjacent?
i will assume yes.

For car A
s(t)=15/3.6*t+.5*.6*t^2
v(t)=15/3.6+.6*t

for car B
s(t)=23/3.6*t-.5*.4*t^2
v(t)=23/3.6-.4*t

when the cars are once again adjacent, the s(t) for each will be the same
15/3.6*t+.5*.6*t^2=
23/3.6*t-.5*.4*t^2

note that t=0 satisfies the equation per my assumption above
the other root is
22.22 seconds

vA(22.22)=17.5 m/s
vB(22.22)=-2.5 m/s

j