bantu jawab secepatnya penting no 14,15,16 pakai cara

14. B
15. f(x,y) = 3x - y
f(0,0) = 3(0) - 0 = 0
f(0,10) = 3(0)-10 = -10
f(8,0) = 3(8)-0 =24 (d)
f(6,4) = 3(6)-4 = 14
mencari nilai x
10x+10y=100 |×4| 40x+40y= 400
16x+8y=128 |×5| 80x+40y= 640 -
-------------------------------------------------
-40x = -240
x = -240/-40
x = 6
subtitusi x = 6 ke pers. 1
10x+10y=100
10(6)+10y=100
60+10y=100
10y= 100-60
10y= 40
y=40/10
y=4