Answer:
17
Step-by-step explanation:
The expression of interest is the difference of the two given expressions.
(-4x +6y) -(-2x -7y) = (9) -(-8)
-2x +13y = 17
The value is 17.
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<em>Additional comment</em>
You could go to the trouble to solve the two equations for x and y, then compute the value of the expression you want. As we saw above, that is not necessary.
The first step in problem solving is always "look at the given information and how it relates to what you are asked." A little time spent doing that can save a lot of effort in the actual problem solving process.
