Question 1013764
x is the number of adults attending the event
y is the number of children attending the event.


x + y <= 150 is one equation.
18x + 9y <= 2475 is the other equation.


x >= 0 is another equation that is implied because the number of adults can't be less than 0.
y >= 0 is another equation for the same reason as in x >= 0.