Calculation:

The given ratios can be simplified further by doing cross product:

\(\displaystyle{\frac{{{3}}}{{{8}}}}={\frac{{{b}}}{{{10}}}}\)

\(\displaystyle{3}{\left({10}\right)}={8}{\left({b}\right)}\)

\(\displaystyle{30}={8}{b}\)

\(\displaystyle{\frac{{{8}{b}}}{{{8}}}}={\frac{{{30}}}{{{8}}}}\)

\(\displaystyle{b}={3.75}\)

The given ratios can be simplified further by doing cross product:

\(\displaystyle{\frac{{{3}}}{{{8}}}}={\frac{{{b}}}{{{10}}}}\)

\(\displaystyle{3}{\left({10}\right)}={8}{\left({b}\right)}\)

\(\displaystyle{30}={8}{b}\)

\(\displaystyle{\frac{{{8}{b}}}{{{8}}}}={\frac{{{30}}}{{{8}}}}\)

\(\displaystyle{b}={3.75}\)