[tex]\it \left.\begin{cases}b+f=32 \Rightarrow b=32-f\\ \\ b+5=f-7|_{-5} \Rightarrow b=f-12\end{cases} \Rightarrow 32-f=f-12 \Rightarrow 32+12=f+f \Rightarrow[/tex]
[tex]\it \Rightarrow 44=2f \Rightarrow 2f=44|_{:2} \Rightarrow f=22\\ \\ b=32-f \Rightarrow b=32-22 \Rightarrow b=10[/tex]