Question

A, 9x - (5 - x)
B, 7x + (2 - 10x) - (x - 4)

Answer 1

A) 9x - 5 + x
10x=5
x=5/10
x=1/2

B) 7x + 2 - 10x - x + 4
-4x+6
-4x=-6
4x =6
x=6/4
x=3/2

Answer 2

A) 9x - (5-x)
9x-5x = 4x

B) 7x + (2-10x) - (x-4)
7x + 8x - 4x
15x - 4x = 11x 

OBS: NÂO ME LEMBRO MUITO BEM DESSA MATÉRIA, CONFIRA ANTES!