X-4y=1 dan x²-5xy + 4y² = 4

X= 4y+1
(4y+1)2 -5(4y+1)y+4y2=4
16y2+8y+1-20y2-5y+4y2=4
3y=3
y=1
x= 4y+1
= 4*1+1
=5