Respuesta :

I believe for number 3, the answer is x=-5 and for number 4, the answer is either x=21 or x=7

Answer:

3). -5. 4).7.

Step-by-step explanation:

3).CB + BA = CA

(x+15) + (x+13) = 18

2x + 28 = 18

2x = 18 - 28

2x = -10

x = -5.

4). ED + DC = EC

(2x - 7) + (x - 6) = 8

3x - 13 = 8

3x = 8 + 13

3x = 21

x = 7.