You can put this solution on YOUR website! if y = 4x, then substitute that in for the bottom equation
make x + y = 5 into x + 4x = 5 then solve
x + 4x = 5
combine like terms
5x = 5
divide both sides by 5
x = 5/5
x = 1
You can put this solution on YOUR website! y= 4X
X+Y=5
substitute for y in the second equation
x +4x = 5
5x = 5
x = 1
y = 4*1
y = 4
solution is x = 1, y = 4