\(\frac{5}{15}\) is the same as \(\frac{1}{3}\) because \(\frac{(5 divided by 5)}{(15 divided by 5)}\)
You have to divide the numerator with the same number that you divide the denominator with. therefore, the answer to the second one is
\(\frac{2}{3}\) because \(\frac{(8 divided by 4)}{(12 divided by 4)}\)