12 n to the 8th power * 13n to the negative 3rd power

Students are given 3 minutes for each multiple-choice question and 5 minutes for each free-response question on a test. there are 15 questions on the test, and students are given 51 minutes to take it.how many multiple-choice questions are on the test?

What is the average rate of change for this function for the interval from x=2 to x=4 ?

This is so hard and it’s for a test