Question

[( x,x + 55) - 31 ] .14 = 560

Answer 1

[( x,x + 55 ) - 31 ] x 14 = 560

( x,x + 55 ) -31 = 560 : 14 

x,x + 55 = 40

x,x = 40 - 55 

x,x = -15

Answer 2

(x.x+15) - 31 = 560 : 14

(x.x+15) -31 = 40

Answer 3

(x.x+55) - 31 = 560:14

(x.x+55) - 31 = 40

x.x+55         = 40 + 31 

x.x + 55       = 71

x.x              = 71 - 55 

x.x              = 16

=>        x = 4     vì  4.4 = 16