Answer
When a real number is substituted, the left hand side will always equal the right hand side.
Work Step by Step
$3x + 6 = 2x + 10 + x - 4$
let $x = 1$
$3(1) + 6 = 2(1) + 10 + (1) -4$
$9 = 9$
let $x = 2$
$3(2) + 6 = 2(2) + 10 + (2) -4$
$12 = 12$
let $x = 3$
$3(3) + 6 = 2(3) + 10 + (3) -4$
$15 = 15$
