Incorrect. The first step is a valid one, and results in x + 10. However, subtracting 5 would result in x + 5. You probably forgot to multiply 5 by 2 when you multiplied $\displaystyle\frac{{1}}{{2}}{x}\usepackage{cmbright}\Huge\$ by 2. To isolate the variable, you must perform the inverse of the operation in the expression in the correct order. Subtracting 5 first yields an expression of $\displaystyle\frac{{1}}{{2}}{x}\usepackage{cmbright}\Huge\$ , and then multiplying by 2, which is the inverse of dividing by 2, yields x by itself. So the correct method is to subtract 5, and then multiply by 2.