Three times as many children as adults attended a concert on Saturday. An adult's ticket cost $7 and child's ticket cost $3. the theater collected a total of $6,000. How many people bought tickets?

Answer 1

3a = c

7a + 3c = 6000

Substitute 3a for c in the second equation and solve for a, then solve for c.

Answer 2

7a+3(3a)=6000
7a+9a=6000
16a=6000
a=375