Just need help showing work

1. A roller coaster car uniformly picks up speed as it rolls down a slope. As it starts down the slope, its speed is 4 m/s. But 3 seconds later, at the bottom of the slope, its speed is 22 mis What is its acceleration? 6 ms 2. A cyclist accelerates from 0 m/s to 8 m/s in 3 seconds. What is his acceleration? Is this acceleration higher than that of a car which accelerates from 0 to 30 m/s in 8 seconds? The cyclist's total acceleration is 2.7ms while that of a car is 3.8ms so the rider's acceleration was definitely not greater than the cars. A car advertisement states that a certain car can accelerate from rest to 70 km/h in 7 seconds Find the car's acceleration. Answer in units of mis 0.28ms/2 (to the second that's what i meant sorry) 4. A lizard accelerates from 2 m/s to 10 m/s in 4 seconds. What is the lizard's average acceleration? 2m/s to the second 5. If a Ferrari, with an initial velocity of 10 m/s, accelerates at a rate of 7 m/s for 3 seconds, what will be its final velocity? 31m/s 6. A speedboat initially moving at 15 m/s slows down to a stop with an acceleration of -1.5 m/s How much time passes during this change in velocity? 10s