Ans: A
$\begin{array}{rcl}
7a + 5b & = & 3a + 8b \\
4a & = & 3b \\
\dfrac{a}{b} & = & \dfrac{3}{4} \\
a : b & = & 3 : 4
\end{array}$
$\begin{array}{rcl}
7a + 5b & = & 3a + 8b \\
4a & = & 3b \\
\dfrac{a}{b} & = & \dfrac{3}{4} \\
a : b & = & 3 : 4
\end{array}$
