Mary is paid 7.5% commission on all of her sales. She had sales of $2300 for the month of December. How much commission did Mary make?

Answer: $172.50

Step-by-step explanation:

$2300 x 0.075 = $172.50

You can double check quickly because you know 10% of 2300 is $230, so 5% is $115. The answer is halfway between the 5% and 10% numbers, so you know it is reasonable.