Question 231215
x+6y=24 multiply by 6 & add.
-6x+5y=-21
6x+36y=144
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41y=123
y=123/41
y=3 ans. 
x+6*3=24
x+18=24
x=24-18
x=6 ans.
Proof:
-6*6+5*3=-21
-36+15=-21
-21=-21