20a + 4b - 9a + 3 = 11a + 4b + 3
2x+5y=21, x+y=3
y=3-x
2x+5y=21
2x+5(3-x) =21
2x+15-5x=21
2x-5x+15=21
-3x+15=21
-3x=21-15
-x=6/3
-x=2
x=-2
I honestly don't know if this is correct but it might be i think its the middle one y=f(x)=x to the second power
