Motion in 1 dimension easy question?

[pmorshad]

a car starts from rest travels for 5.0s with a uniform acceleration of + 1.5m/s^2. The driver then applies the brakes, causing uniform acceleration of -2.0m/s^2. If the brakes are applies for 3.0s (a) how fast is the car going atthe end of the braking period and b how far has it gone

I have already done part a and i have the answers for both parts i just don't know the steps in approaching part b
the answer to b is 32.2m
please help! thank you :D

 

[conquerer7]

When it's speeding up, it starts at 0 m/s and after the speedup is at 7.5 m/s. That's an average of 3.75 m/s for 5 seconds, so the distance traveled during this part is 18.75 m.

When it begins to brake, it's going at 7.5 m/s, and then after the braking is at 1.5 m/s. That's an average of 4.5 m/s during this period of 3 seconds, so during the braking it moves 13.5 meters.

The sum is 32.25 meters.

 

[pmorshad]

but what equation did you use?

 

[conquerer7]

x = t (v_i + v_f) / 2