<span>Integer numbers prime factorization: 20 = 22 * 5; 108 = 22 * 33;Take all the common prime factors, by the lowest powers.Greatest (highest) common factor (divisor), gcf, gcd: gcf, gcd (20; 108) =<span> 22</span> = 4;</span><span>Step 2: Divide fraction's both numerator and denominator by their greatest common factor (divisor), gcf (gcd)</span>