SOLUTION: Match x=7y+11 3x+20y=99 12x-7y=11 3x+20y=99 which is substitution and addition method? How did you conclude your answer

Question 179434: Match
x=7y+11
3x+20y=99
12x-7y=11
3x+20y=99
which is substitution and addition method?
How did you conclude your answer
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
We can solve the first system by substitution. We could use elimination/addition, but substitution is much easier. Why? Notice how "x" is already isolated. So we can simply plug in in the second equation and solve for "y"

The second system can be solved much easier via elimination/addition. If we multiply the second equation by -4, we get . If we add this new equation to equation 1, the "x" terms will cancel out which will let us solve for y.
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