*5x + 2y = 20
where:
x = number of adults
y = number of children
intercepts 'y' ---> x=0
5x + 2y = 20
2y = 20 - 5x
y = 20/2 - 5/2x
y = 10 - 5/2x
y = 10 - 5/2(0)
y = 10

(0, 10)
this means that first there were 10 children
Intercep 'x' ----> y=0
5x + 2y = 20
5x = 20 - 2y
x = 20/5 - 2/5y
x = 4 - 2/5(0)
x = 4

(4,0)
this means that first there were 4 adults