Algebra story problem

Question

The admission fee at an amusement park is $3.50 for children and $7.00 for adults. On a certain day, 229 people entered the park, and the admission fees collected totaled 1239 dollars. How many children and how many adults were admitted? 

Answer 1

x+y = 229

3.5x + 7y = 1239

3.5x + 7(229 - x) = 1239

3.5x + 1603 - 7x = 1239

1603 - 3.5x = 1239

-3.5x = -364

x=104

y=125

104 children and 125 adults