## Algebra: A Combined Approach (4th Edition)

$\frac{3}{10}$
1. Write numerator and denominator as product of primes: $\frac{12}{40}$ = $\frac{2 * 2 * 3}{2 * 2 * 2 * 5}$ 2. Separate common factors by writing as fraction equal to 1: $\frac{3}{2 * 5}$ * $\frac{4}{4}$ = $\frac{3}{2 * 5}$ = $\frac{3}{10}$