x = number of children entered park
306-x = number of adults entered park
306 total people
1.5x = fees from children
4(306-x) = fees from adults
734 = total fees
1.5x + 4(306-x) = 734
1.5x + 1224 - 4x = 734
-2.5x = -490
x = 196
306 -x = 110
196 children and 110 adults