The solution is (x, y) = (5, 16). My "work" is to make use of a graphing calculator.
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You can subtract the second equation from the first. This gives
... 0 = 3x -15
Then, divide by 3 and add 5.
... 0 = x - 5
... 5 = x
Substitute this value into either equation to find y.
... y = 2x +6
... y = 2·5 +6
... y = 16
The strategy to subtract the second equation from the first is based on the observation that both equations give expressions for y, and the x-coefficient in the first equation is the larger of the two x-coefficients. Thus, the subtraction we chose will eliminate y and give an x-term with a positive coefficient.
