Using the given formula, the length is equal to $\displaystyle\frac{{{36}{{x}}^{{2}}}}{{{4}{x}}}\usepackage{cmbright}\Huge\$ . Divide the variables by subtracting the exponents. Because the x in the denominator did not have an exponent, you may have thought that you did not need to subtract anything. Remember that no exponent is the same as an exponent of 1.