I need some help and explanation of A and B please.

Problem 8: Suppose a hot tub containing 1500 kg of water is heated from 10.0 C to 40.0'C by an electric immersion heater. 19 Part (a) What is the cost, in dollars, of heating the hot tub, assuming 75.0% efficiency (to account for heat loss to the surroundings)? The cost of electricity is 11.5 cents/k Wh. Numeric : A numeric value is expected and not an expression. cost = Part (b) What current, in amperes, does the 220-V AC electric heater run on, if it took 3.5 h to heat up the water? Numeric : A numeric value is expected and not an expression. I=