This is an expression, not an equation (no equality sign).
y'+e2x-y=0?
If so:
y'-y=-e2x.
Use integration factor e-x:
e-xy'-e-xy=-e2x-x,
d(e-xy)/dx=-ex,
e-xy=-∫exdx,
y/ex=-ex+C, where C is an arbitrary constant,
y=-e2x+Cex.
CHECK
y'=-2e2x+Cex,
y'+e2x-y=-2e2x+Cex+e2x+e2x-Cex=0 (terms with the same colour cancel out).