Physics acceleration questions please help

1.)A car is traveling at a constant speed of 16 m/s on a highway. At the instant this car passes an entrance ramp, a second car enters the highway from the ramp. The second car starts from rest and has a constant acceleration. What acceleration must it maintain, so that the two cars meet for the first time at the next exit, which is 1.0 km away?

2.)Starting from rest, a speedboat reaches a speed of 4.2 m/s in 2.5 s. What is the boat's speed after an additional 3.6 s has elapsed, assuming the boat's acceleration remains the same?

i know its a lot but i have to do them for a class online, and i haven't learned any acceleration yet and knowing how to do these would help with all the others.

1)
t = D/v1 = 1000/16 = 62.5 sec
D = ½a*t² → a = 2D/t² = 2*1000/62.5²

a = .512 m/s²

2)
a = dv/dt = 4.2/2.5 = 1.68 m/s²