The zoo charges 15.00 for adult admission and 5.00 for each child. The total bill for 144 people was 1,140. How many adults and how many children went to the zoo?

x+y=144.

15x+5y=1140.

15x+5(144-x)=1140.

15x+720-5x=1140.

20x=1140-720.

20x=420.

x=420/20=21.

y=144-21.

=123.