Graphing Help!

1. We can plug in $(1,2)$ for both equations

$x=\frac{1}{4}y+a\rightarrow 1=\frac{2}{4}+a\rightarrow\boxed{a=\frac{1}{2}}$

$y=\frac{1}{4}x+b\rightarrow2=\frac{1}{4}+b\rightarrow\boxed{b=\frac{7}{4}}$

2. Then add:

$\frac{1}{2}+\frac{7}{4}=\boxed{\frac{9}{4}}$

That is the answer