Answer:
(a) Current flowing through truck battery is 180 A
(b) Time taken in calculator is 333.33 s
Explanation:
(a) Given:
The charge on the truck battery,q = 720 C
Time, t = 4.00 s
Consider I be the current flowing through truck battery.
The relation between current, charge and time is:
I = q/t
Substitute the suitable values in the above equation.

I = 180 A
(b) Given:
The charge on the calculator,q = 7.00 C
The current flowing through calculator, I = 0.3 mA = 0.3 x 10⁻³ A
Consider t be the time.
The relation between current, charge and time is:
t = q/I
Substitute the suitable values in the above equation.

I = 333.33 s