Total muffins and doughnuts = 18
Assumed all doughnuts = 18 x $0.4 = $7.20
But she paid $9.15.
$9.15 - $7.20 = $1.95
$1.95 must have been used to pay for the muffin.
Difference in price between muffin and doughnuts:
$0.55 - $0.40 = $0.15
Number of muffins bought = $1.95 ÷ 0.15 = 13
She bough 13 muffins.
Number of doughnut bought = 18 - 13 = 5
She bought 5 doughnuts
Answer: She bought 5 doughnuts and 13 muffins.
