diketahui x-3y-5=0 dan 2x-5y=9. Nilai dari 3x + 2y adalah.....

x - 3y = 5 |×2|
2x - 5y = 9 |×1|

2x - 6y = 10
2x - 5y = 9
________ _
-y = 1
y = -1

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

3x + 2y
= 3(2) + 2(-1)
= 6 - 2
= 4