Answer: $3.17
Explanation: to find the cost of the milkshakes, you multiply $7.92 by the amount of milkshakes (2), which would make the total $15.84. Then to find %20 of $15.84, you multiply it by 0.20. This is because when you multiply by a percent, you move the decimal point to the left by two numbers. In this case, %20 of the cost of the milkshakes will be roughly $3.17 after rounding to the nearest hundredths place. :)