we'll first conver the mixed fraction to "improper".
for A) is very simple, is just the difference of both.
for B) is the difference of 9 innings and what has been pitched already.
[tex]\bf \stackrel{mixed}{1\frac{2}{3}}\implies \cfrac{1\cdot 3+2}{3}\implies \stackrel{improper}{\cfrac{5}{3}}
\\\\\\
A)\\\\
\stackrel{start~pitcher}{5}-\stackrel{relief~pitcher}{\cfrac{5}{3}}\quad \stackrel{LCD~of~3}{\implies }\quad \cfrac{15-5}{3}\implies \cfrac{10}{3}\implies 3\frac{1}{3}
\\\\\\
B)\\\\
9-\left( 5+\cfrac{5}{3} \right)\implies 9-\left( \cfrac{15+5}{3} \right)\implies 9-\cfrac{20}{3}
\\\\\\
\textit{LCD of 3}\qquad \cfrac{27-20}{3}\implies \cfrac{7}{3}\implies 2\frac{1}{3}[/tex]
