The question gives us an expression:
[tex]12x+4y=20[/tex]We are told to solve for y. This means making y the subject of the formula.
Let us perform these operations below:
[tex]\begin{gathered} 12x+4y=20 \\ 4\text{ is common in the whole expression} \\ 4(3x)+4(y)=4(5) \\ \text{This means we can divide both sides by 4} \\ \frac{1}{4}\mleft(4(3x)+4(y)\mright)=\frac{1}{4}(4(5)) \\ \\ \frac{4(3x)}{4}+\frac{4y}{4}=\frac{4\mleft(5\mright)}{4}\text{ (4 crosses out)} \\ \\ 3x+y=5 \\ \text{Subtract 3x from both sides} \\ 3x+y-3x=5-3x \\ 3x-3x+y=5-3x \\ y=-3x+5\text{ (Option A)} \end{gathered}[/tex]Therefore the final answer is:
y = - 3x + 5
