question

if i needed 80 people to go to the zoo, $6 for an adult and $3 for children and $336 was made,

how many children and adults when to the zoo?

Let x = adults
Let y = children

$\begin{array}{|rcll|} \hline & 6x + 3y &=& 336 \quad & | \quad : 3 \\ (1) & 2x + y &=& 112 \\ (2) & x + y &=& 80 \\\\ \hline (1)-(2): & (2x + y) - (x + y) &=& 112-80 \\ & 2x + y - x - y &=& 112-80 \\ &\mathbf{x} &\mathbf{=}& \mathbf{32} \\\\ & x + y &=& 80 \\ & 32 + y &=& 80 \\ & y &=& 80 - 32 \\ &\mathbf{y} &\mathbf{=}& \mathbf{48} \\ \hline \end{array}$

32 adults and 48 children went to the zoo.