tolong dibantu ya teman2

A/4 + B/10 = 9 |20| 5A + 2B = 180 .... (1)
B/6 - C/10 = 1 |30| 5B - 3C = 30 .... (2) => B = (30 + 3C)/5
C/4 + A/6 = 14 |12| 3C + 2A = 168 ... (3) => A = (168 - 3C)/2
------------------------------------------------------- +
................................. 7A + 7B = 378
=> A + B = 54
=> (168 - 3C)/2 + (30 + 3C)/5 = 54 ===> kali 10
=> 5(168 - 3C) + 2(30 + 3C) = 540
=> 840 - 15C + 60 + 6C = 540
=> -9C = 540 - 840 - 60
=> C = -360/-9 = 40

Jadi A + B + C = 54 + 40 = 94