If $2x+3y=34$ and $\frac{x+y}{y}=\frac{13}{8}$, then find the value of $5y+7x$.
Answer
Answer (as printed):
Explanation
The given equations are: $2x+3y=34$ …(i) and $\frac{x+y}{y}=\frac{13}{8} \Rightarrow 8x+8y=13y \Rightarrow 8x-5y=0$ …(ii). Multiplying (i) by 5, (ii) by 3 and adding, we get: $34x=170$ or $x=5$. Putting $x=5$ in (i), we get $y=8$. $5y+7x=(5\times8+7\times5)=40+35=75$.
Explanation as extracted from the printed page; notation may be imperfect.