Milk is 2.89 a gallon. if each geralds four children drinks 0.5 gallons of milk per week how much does he spend each week on milk?

Amount of milk drunken:  (4 children)(0.5 gall per week per child)

Multiply the result of the above calculation by ($2.89 / gallon):

4(0.5)($2.89) = $5.78 per week milk expenditure