Tolong no 12 sampai 16 yaa..

12. 3x+5y=25 *4 | 12x+20y=100
4x-7y=6 *3 | 12x-21y=18
______________+
41y=82
y=2
4x-7y=6
4x-7(2)=6
4x=6+14
4x=20
x=5
11x+8y= 11(5)+8(2)
=55+16
=71