You may have multiplied the reciprocal of the first number by the second number: $\displaystyle\frac{{4}}{{3}}\cdot\frac{{9}}{{10}}\usepackage{cmbright}\Huge\$ . To solve the problem, multiply the first number by the reciprocal of the second number:
$\displaystyle\frac{{3}}{{4}}\div\frac{{9}}{{10}}=\frac{{3}}{{4}}\cdot\frac{{10}}{{9}}\usepackage{cmbright}\Huge\$