The charge on a capacitor is given by the following Q=4t + 5 (mc). What is the value of the charging current?

Answer 1

The first answer is correct in approach. Current is defined as the time rate of change of charge: i = dq/dt

Differentiating, you obtain:
i = 4 milliColoumbs/sec = 4 mA

Answer 2

current is charge per second, so assuming t is in seconds and your (mc) is milli-Coloumb then the take the derivative. I get 4 mA.