Sederhanakan bentuk aljabar berikut a. 7a+2b-8a+(-4b) b.(16a-10b +5)-(5a-4b+3c) c.(4x+5y+7)-(-5x-6y+9)

a) 7a + 2b - 8a + (-4b)
= 7a - 8a + 2b - 4b
= - a - 2b

b) (16a - 10b + 5) - (5a - 4b + 3c)
= 16a - 5a - 10b + 4b - 3c + 5
= 11a - 6b - 3c + 5

c) (4x + 5y + 7) - (-5x - 6y + 9)
= 4x + 5x + 5y + 6y + 7 - 9
= 9x + 11y - 2