What is 4/5 multiplied by 10 subtracted by 3 and 1/2?

There are 15 plates and each plate is either 7 or 12 inches diameter. which systems of equations do you use to find the number of 7 inch plates, x and 12 inch plates, y

Use the quadratic formula to solve the equation. if necessary, round to the nearest hundredth. x^2 - 8 = -6x a. –7.12, 1.12 b. 7.12, –1.12 c. 7.12, 1.12 d. –7.12, –1.12

Solve 2 - 3 cos x = 5 + 3 cos x for 0° ≤ x ≤ 180° a. 150° b. 30° c. 60° d. 120°