# SAT Math Multiple Choice Practice Question 451: Answer and Explanation

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**Question: 451**

**13.** If *x* + 2*y* = 20, *y* + 2*z* = 9, and 2*x* + *z* = 22, what is the value of *x + y + z* ?

A. 10

B. 12

C. 17

D. 22

E. 51

**Correct Answer:** C

**Explanation:**

**C** Stack all three equations and add them together to get 3*x* + 3*y* + 3*z* = 51. Factor out a 3 to get 3(*x + y + z*) = 51. Divide both sides by 3 to get *x + y + z* = 17.