[单选题]
A cart starts from r- j;axiri ;4h*q4 vhiwe; kl x(t5fzczpiu2n+- st and accelerates at $4.0 \; m/s^2$ for 5.0 s, then maintain that velocity for 10 s, and then decelerates at the rate of $2.0 \; m/s^2$ for 4.0 s. What is the final speed of the car?