@py
Bài làm :
`a/5 + b/3 = (13)/(15)`
`⇔ (a . 3)/(15) + (5 . b)/(15) = (13)/(15)`
`⇔ a . 3 + 5 . b = 13`
`⇔ a . 3 + 5 . b = 3 + 10`
`⇔` \(\left[ \begin{array}{l}a.3=3\\5.b=10\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}a=1\\b=2\end{array} \right.\)
Vậy `(a;b) = (1;2)`