jika 5x+6y=30 dan 6x+10y=80 tentukan nilai dari 3x-2y=...

5x + 6y = 30
5x = 30 - 6y
x = 6 - 6/5y

6(6 - 6/5y) + 10y = 80
36 - 36/5y + 10y = 80
-36/5y + 10y = 80 - 36
-36/5y + 50/5y = 44
14/5y = 44
14y = 220
y = 220/14
y = 110/7

x = 6 - 6/5y
x = 6 - 6/5 (110/7)
x = 6 - 132/7
x = 42/7 - 132/7
x = -90/7


3x - 2y = 3(-90/7) - 2(110/7)
= -270/7 - 220/7
= -490/7
= -70