It appears that you rewrote the fractions correctly, but then you subtracted incorrectly. When you simplify the expression $\displaystyle-{\left({3}{x}+{15}\right)}\usepackage{cmbright}\Huge\$ , remember to distribute the minus sign on the outside to the term 15. The correct answer is: $\displaystyle\frac{{{5}{x}+{1}}}{{{{x}}^{{2}}+{7}{x}+{10}}}\usepackage{cmbright}\Huge\$