Answer:
Gọi hai số phải tìm là x và y
Có: \(x + y = 63 , 5 \)
\(⇒ x + x × 10% + y + y × 25% = 75 , 115 \)
\(\text{⇔ x + x × 10% + y + y × 10 % + y × 15% = 75 , 115 }\)
\(\text{⇔ ( x + y ) × 110% + y × 15% = 75 , 115 }\)
\(\text{⇔ 63 , 5 × 110% + y × 15% = 75 , 115 }\)
\(\text{⇔ 69,85 + y × 15% = 75 , 115 }\)
\(\text{⇔ y × 15% = 75 , 115 - 69,85}\)
\(\text{⇔ y × 15% = 5,265}\)
\(\text{⇔ y = 5,265 : 15% }\)
\(\Leftrightarrow\hept{\begin{cases}x=35,1\\y=28,4\end{cases}}\)