number of children tickets

Question

At the city museum, child admission is $5.20 and adult admission is $8.50. On Sunday, three times as many adult tickets as child tickets were sold, for a total sales of $644.70. How many child tickets were sold that day?

Answer 1

5.20C + 8.50A = 644.7

A= 3C

5.2C + 8.5(3C) = 644.7

5.2C + 25.5 = 644.7

30.7C = 644.7

C = 644.7/30.7 = 21 Children

A =3C = 3(21) = 63 Adults

check the answers

5.2(21) + 8.5(63)

= 109.2+ 535.5= 644.7