Question

13 + X - 4 = X + X -7 =

Answer 1

13+x-4=x+x-7 agrupar x
-x=-16 multiplicar por -1
x=16
saludos

Answer 2

13 + x  - 4 = x+x-7
x-x-x = 4-7-13
-x = -16
x = 16

Comprobación:
13+16 -4 = 16+16-7
29-4 = 32-7
25 ≡ 25

Respuesta:
x = 16