Jika x+y=2 dan x-2y=5,maka nilai dari 4x-4y=

x + y = 2
x - 2y = 5
------------------ -
3y = -3
y = -1

x + y = 2
x + (-1) = 2
x - 1 = 2
x = 2 + 1 = 3

4x - 4y
= 4(3) - 4(-1)
= 12 + 4
= 16

SPLDV

x + y = 2
x -2y = 5
------------- --
3y = -3 → y = -1
...
x + (-1) = 2 → x = 3
maka :
4x - 4y => 4(3) - 4(-1) = 12+4 = 16