\[a > b;\ \ так\ как:\]
\[\frac{3}{8}a = \frac{b \cdot 72}{100}\]
\[\frac{3 \cdot 125}{8 \cdot 125}a = \frac{72 \cdot 10}{100 \cdot 10}b\]
\[\frac{375}{1000}a = \frac{720}{1000}b\]
\[0,375 < 0,720 \Longrightarrow a > b.\]