Solving a value mixture problem using a linear equation

Question

At the movie theatre, child admission is $5.10

 and adult admission is $9.10

. On Thursday, four times as many adult tickets as child tickets were sold, for a total sales of $913.00

. How many child tickets were sold that day?

Answer 1

Say c child tickets were sold

Then 4c adult tickets were sold

Total income : 4c x 9.10 + c x 5.10 = 41.5c = 913

So c = 913 / 41.5 = 22

Mike