For a), use the definition of current. where I is the current, q is the charge and t is the time. In this case the current is constant. Therefore this gives,
For, b) you should know that the energy expended is given by, where V is the terminal volatage. Hope you know have a idea why the terminal voltage expression is given.
For c), first find out the kilowatt hours that had been used because of the charging. The power is given by, . You will have to multiply this with the hours used. Then use the given cost per kWh to estimate the charging cost.
Hope you will be able to continue.