To answer the equation 3a – 4b = 21 , we substitute each point in the given choices to the given expression. In this case, a. 3(-2) - 4(-3) = 6b. 3(0) - 4(7) = -28c. 3(7) - 4(0) = 21d. 3(-3) - 4(-2) = -1 The point that is equal to 21 when substituted is C.
