Question

si X + 30 = X • 4
¿Cuánto vale X?

Answer 1

x+30 = 4 . x
30 = 3x 
x = 10

Answer 2

x + 30 = x * 4

x + 30 = 4x

x - 4x = - 30

- 3x = - 30

x = -30/-3

x = 10

Solución : 

x = 10