Answer:
5.76
Step-by-step explanation:
Easy way to work with percentage is to take the decimal and move it over one to the left and that will give you 10%.
Since you 38.40 move the decimal over one to the left and you'll get 3.84. That is 10%, but since you need 15% divide 3.84 by two to get 5%- that is 1.92.
3.84 (10%) + 1.92 (5%) = 5.76 (15%)