Let x be the number. With this representation, double this number is 2x and thrice is 3x. We are asked to give an expression for the difference (subtraction) of these numbers, the answer to this question should be, 3x - 2x
If an expression is shown as 5(x+2) the numbers inside the parenthesis must both be multiplied by the number outside. Only x was multiple. The correct rewritten expression would be 5x+10