Every day, Billie bakes 3 pumpkin pies for 11 days and puts them in the refrigerator.  It takes 2 cans of whipped cream to cover 1 pie.  If Tiffany comes over and eats 4 pies, how many cans of whipped cream does Billie need to buy to cover the remaining pies?
In total Billie bakes 3 x 11 = <T>multiply(3, 11)=33 pies.
After Tiffany eats the pies, this many pies are in the refrigerator: 33 - 4 = <T>subtract(33, 4)=29 pies.
She needs to buy this many cans of whipped cream 29 x 2 = <T>multiply(29, 2)=58 cans.
