A student raises her grade average from a 75 to a 90. What was the percent of increase in the student’s grade average? Round your answer to the nearest tenth of a percent, if necessary

Here are some formulas...
percent increase = (new number - original number) / original number...* 100
percent decrease = (original number - new number) / original number...* 100

a student raises her grade from a 75 to a 90since it is going from a smaller number to a larger number, u have an increase
percent increase = (90 - 75) / 70* 100
= 15/70 * 100
= 0.2142 * 100
= 21.42 rounds to 21.4% increase

36.50 on sale for 32.12...since it goes from a larger number to a smaller number, u have a decrease
percent decrease = (original number - new number) / original * 100
= (36.50 - 32.12) / 32.12...* 100
= 4.38 / 32.12...* 100
= 0.1363...* 100
= 13.63 rounds to 13.6% decrease

23.5 to 21.2this is a decrease
percent decrease = (original number - new number) / original...* 100
= (23.5 - 21.2) / 23.5* 100
= 2.3 / 23.5* 100
= 0.0979 * 100
= 9.79 rounds to 9.8% decrease

Z-gadgets has developed a mini-laptop that will be marketed in developing countries. it is estimated that the requirement for the new product will start out slow and accelerate as the product becomes increasingly familiar to worldwide consumers. to begin to staff the new production facilities, the company should conduct a(n):   demand forecast