Question

use the prime factorization method to find the least common denominator then find the sum or the difference

Answer 1

$\frac{5}{8}-\frac{4}{9}$

LCD = Lowest Common Denominator.

The prime factors of the denominators are as follows

$\begin{gathered} 8=2\times2\times2=2^3 \\ 9=3\times3=3^2 \end{gathered}$

The LCD will be

$\begin{gathered} 2^3\times3^2=72 \\ \text{LCD}=72 \end{gathered}$$\frac{5}{8}-\frac{4}{9}=\frac{45-32}{72}=\frac{13}{72}$