Question

The St. Mark’s Community Barbecue
served 250 dinners. A child’s plate cost $3.50 and
an adult’s plate cost $7.00. A total of $1347.50 was
collected. How many of each type of plate
was served?

Answer 1

Let C = Child's Plate
Let A = Adult's Plate

C + A = 250
3.5C + 7A = 1347.50

Multiply the first equation by 7 to find what C is and you get:

7C + 7A = 1750
3.5C + 7A = 1347.50 Subtract this equation from the first one and you get:

3.5C = 402.50
C = 115 Substitute this value into the following equation:

C + A = 250
115 + A = 250
A = 135

Therefore, 115 Child's Plates and 135 Adult's Plates were served