[tex]\it b-a=9\ \ \ \ \ (*)\\ \\ \\ \{b,\ \ a\}\ d.\ p.\ \{8,\ \ 5\}\Rightarrow \dfrac{b}{8}=\dfrac{a}{5}=\dfrac{b-a}{8-5}\ \stackrel{(*)}{=}\ \dfrac{9}{3}=3\\ \\ \\ \dfrac{a}{5}=3 \Rightarrow a=5\cdot3=15\\ \\ \\ \dfrac{b}{8}=3 \Rightarrow b=8\cdot3=24[/tex]
