Answer:
To check if the solution is right you substitute.
Explanation:
So in this case you put y = - 6
So you substitute the y as - 6
12(5+2y) = - (6-9y)+4y
12(5+ (2 times - 6)) =(6-(9 times - 6)) + (4 times - 6)
12 times (5+-12) = (6- -6) + - 24
12 times - 7 = 12+-24
-84 = - 12
And that's how to check it basically.