![\begin{gathered} \text{Given} \\ a+c=65 \\ 7a+4c=335 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/dqjht7s6pml77js3bup7736ak0t8vxxcem.png)
Solve by substitution, use the first equation and solve in terms of c
![\begin{gathered} a+c=65 \\ c=65-a \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/84udme3i53aeym62zunzlxea5f10z2tob1.png)
Substitute this to the second equation and solve for a
![\begin{gathered} 7a+4c=335 \\ 7a+4(65-a)=335 \\ 7a+260-4a=335 \\ 7a-4a=335-260 \\ 3a=75 \\ (3a)/(3)=(75)/(3) \\ a=25 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/mm4un2calcj5qnwyg9gfcx5qx4mhu1ogtx.png)
Substitute the value of a back to the first equation
![\begin{gathered} a+c=65 \\ 25+c=65 \\ c=65-25 \\ c=40 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/iup6inoxln4uudxce18y0an73iwgqavpi4.png)
With a = 25, and c = 40, we can conclude that there are 25 adult tickets, and 40 child tickets sold on Saturday.