The average rainfall in july last year was 1.5 last july was -0.36 inches. how much rain fell last july?

The common difference, d, can be determined by subtracting the two consecutive values:

1 - 5 = -4
-3 - 1 = -4
-7 - -3 = -4

Then, using the equation:

an = a1+ d(n-1)
a_21 = 5 + (-4)(21 - 1)
a_21 = -75

The answer is letter D. I hope I was able to help you. Have a good day!