[tex]\frac{1}5x-\frac{2}3y=30[/tex]
Plug in 15 for y.
[tex]\frac{1}5x-\frac{2}3(15)=30[/tex]
2/3 of 15 is 10.
[tex]\frac{1}5x-10=30[/tex]
Add 10 to each side.
[tex]\frac{1}5x=40[/tex]
Divide each side by 1/5.
(dividing by a fraction is the same as multiplying by its reciprocal...flip 1/5...×5)
[tex]\boxed{x=200}[/tex]