He has a total of 431 ounces and each cupcake needs 8 ounces of frosting. Therefore can divide the total amount of frosting (431 ounces) by the amount per cupcake (8 ounces)
total amount/ amount per cupcake
431 ounces/8 ounces
431/8
53.875
0.875, or a fraction/part of a cupcake can’t be frosted, so we should round down to the nearest whole number.