Tolong yang bisa darurat

(7a + 6b - 3c) + (6a - 8b + 5c)
= 7a + 6b - 3c + 6a - 8b + 5c
= 13a - 2b + 2c

(7a + 6b - 3c) - (6a - 8b + 5c)
= 7a + 6b - 3c - 6a + 8b - 5c
= a + 14b - 8c