bantu sya jawab no 6 aj ,dengan caranya!!

Diketahui :
• 2a = 4
• b = -a
• c = ab

Ditanya :
a + b - c = ?

Jawab :
• 2a = 4
a = 4/2
a = 2

• b = -a
b = -2

• c = ab
c = (2)(-2)
c = -4

maka
a + b - c = 2 + (-2) - (-4)
a + b - c = 2 - 2 + 4
a + b - c = 4