On his first two social studies tests, billy made an 86 and a 93. what grade must billy make on the third test to have an average of 90 for all three tests?

15

step-by-step explanation:

we are given the following expression and we are to solve it and find the product:

-13 × (-5)

solving the given expression in the standard order of solving a mathematical expression, beginning with the opening of brackets and then multiplying the terms and changing their signs.

-3 × -5 = 15 (answer is positive because when negative is multiplied with negative, it gives a positive answer)

nothjing

step-by-step explanation: