Help please to solve

Question

At the movie theatre, child admission is $5.60 and adult admission is $9.10. On Saturday, twice as many adult tickets as child tickets were sold, for a total sales of $523.60. How many child tickets were sold that day?

Answer 1

5.6c + 9.1a = 523.6

a = 2c

5.6c + 9.1(2c) = 523.6

5.6c + 18.2c = 523.6

23.8c = 523.6

c = 523.6/23.8 = 22 child tickets

a = 44 adult tickets

5.6(22) + 9.1(44)

= 123.2+ 400.4

=523.6