Question

At the movie theatre, child admission is $5.10 and adult admission is $9.90 . On Sunday, 141 tickets were sold for a total sales of $1031.10 . How many child tickets were sold that day?

Answer 1

let's call amount of child admission tickets x
and adults - y, then:
x+y=141 (total tickets)
5.1*x+9.9y=1,031.10 (total sales)
solve this system for x & y

Answer 2

y=141-x
then:
5.1* x +9.9*(141-x)=1031.10
-4.8*x + 1395.9=1031.10
-4.8x=-364.8
x=76 (child admission tickets)

Answer 3

substitute value of x in original eq & find y:
y=141-76
y=65 (adult admission)