Can you explain how to do this (paper)?

3. A block sits on a cart with a tilted top as shown in the figure. 0 There is no friction between the block and the cart. You push the cart so that the block does not slide up or down the slope. What is the acceleration of the cart? 0 Now there is friction between the block and the cart, with a static friction coefficient p5 = 0.2. What is the smallest and largest acceleration the cart can have so that the block doesn't slide relative to the cart