x = amount of children attended the event
y = amount of adults attended the event
they want to raise $1000, and the organizing costs $200, so the revenue, incoming capital, must be 1000 + 200, so the cost is covered and they're left with the $1000 they're after.
since is $6 per child, and "x" children went to it, they total amount of revenue from the ticket sales for all children is 6*x, or 6x.
since is $8 per adult, and "y" adults went to it, they total amount of revenue from the ticket sales for all adults is 8*y, or 8y.
6x + 8y = 1200.
if the event were attended by only adults, then 8y = 1200.
