$65$ kids at a school voted for their favorite ice-cream flavor. They can vote for up $2$ flavors and the choices are vanilla,chocolate,and strawberry. $10$ kids voted for strawberry, $35$ voted for vanilla,and $25$ people voted for chocolate. Let $A$ be the amount of kids that voted for only vanilla, $C$ be the amount people that voted for chocolate,and $B$ be the amount of people who voted for both.What is $\dfrac{ab}{c}$?
I set up equations and got $\begin{cases}S + B_1+B_3 = 10 \\ V+B_1+B_2 = 35 \\ C= 25 \end{cases}$. It seems hard to solve for $\dfrac{ab}{c} = \dfrac{V*B_1}{25}$