You may not have noticed the 8 in front of the parentheses on the right side and simplified the equation to $\displaystyle{17}{x}-{7}={3}{x}-{7}\usepackage{cmbright}\Huge\$ . The correct simplifications would give you $\displaystyle{17}{x}-{7}={16}{x}+{8}+{x}-{8}\usepackage{cmbright}\Huge\$ . The correct answer is that there is no solution.