Need major help. Step-by-step with the numbers so I can understand it would be terrific.

A 20 cm radius ball is uniformly charged to 70 nC.

(a) What is the ball's charge density?

(b) How much charge is enclosed by spheres of radii 5, 10, and 20 cm?

(c) What is the electric field strength at points 5, 10, and 20 cm from the center?