#### Answer

$\frac{-73}{120}$

#### Work Step by Step

To subtract 2 fractions, we also need to convert them into a common denominator, just like when we add. In this case, we need to find a common multiple between 24 and 10. Since 120 is the smallest number divisible by both 24 and 10, it is our denominator.
When multiplying a denominator by any number, to keep the value of that fraction unchanged, we must also multiply the numerator by that number.
$\frac{7}{24}-\frac{9}{10}=\frac{7*5}{24*5}-\frac{9*12}{10*12}=\frac{35}{120}-\frac{108}{120}=\frac{35-108}{120}=\frac{-73}{120}$