THE CORRECT ANSWER IS (C). THIS PROBLEM INVOLVES A SYSTEM OF THREE...

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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