1a. Earnings each week = (4 h)*($7.20/h) = $28.80
Savings each week = $28.80 - 10.00 = $18.80
Savings after 12 weeks = 12*$18.80 = $225.60
Grandparents' gift = 0.25*$225.60 = $56.40
Account balance after Grandparents' gift = $225.60 + 56.40 = $282.00
1b. Father's gift = 0.15*$225.60 = $33.84
Account balance after both gifts = $282.00 + 33.84 = $315.84