I have two questions for you guys. The first one should be simple yet the program used for our homework isn't accepting my answer. I'm really lost on the second question. Thanks for the help in advance.

First Question

In the figure below, a ball is shot directly upward from the ground with an initial speed of v0 = 7.60 m/s. Simultaneously, a construction elevator cab begins to move upward from the ground with a constant speed Vc = 4.00 m/s.

What maximum height does the ball reach relative to the floor of the elevator cab?

Using a kinematic equation, I found the maximum height the ball reaches which is 2.9469 m. The ball reaches its maximum height in .77551 s. I think I am misunderstanding the question, but should I just find the change in y for the elevator cab in .77551 s and subtract the change in y for the ball from the change in y for the cab?

Second Question

In the figure below, two blocks are connected over a pulley. The mass of block A is 15 kg, and the coefficient of kinetic friction between A and the incline is 0.22. Angle θ is 30°. Block A slides down the incline at constant speed. What is the mass of block B?

With constant speed, the forces acting on Block A should be 0. As a result, you should sum up the forces acting on the block.

I got for Block A: T-Wsin(x)+f=0

After this, I am completely lost. Inclined planes are not my strong suit.

Thanks for the help in advance.