Algebra help! How many of each ticket was sold?

Question

Suppose 600 tickets were sold for a concert with a total revenue of $2,800. If the adult tickets were $7 and the student tickets were $3.50, how many of each type of ticket was sold?
Adult: ____
Student: _____

Answer 1

Lets 'a' represents adult tickets and 's' represents student tickets

a + s = 600---->(1)

7a + 3.5s= 2800------>(2)

multiply the equation (1) by 7

Substract equation (1) with (2)

7a  +  7s   = 4200

7a  + 3.5s = 2800

(-)      (-)        (-)
--------------------------

          3.5s = 1400

s = 1400 / 3.5 = 400

substitute s = 400 in equation (1)

a + 400 =600

a = 600 - 400

a = 200

adult tickets = 200

student tickets = 400