2. The correct answer is (C). This problem involves a system of three equations with
three variables. One way to solve it is with both the substitution and addition-
subtraction methods. Express x in terms of y: x 5 8 – y. Substitute this expression for x
in the second equation: (8 2 y) 1 z 5 7 or 2y 1 z 5 21. Add this equation to the third
equation in the system.
2y 1 z 5 21
y 1 z 5 6
2z 5 5
z 5 2.5
To find the value of x, substitute z’s value for z in the second equation:
x 1 2.5 5 7; x 5 4.5
634 PART VI: Five Practice Tests
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