Question

Devon and his friends bought strawberry wafers for $3 per packet and chocolate wafers for $1 per packet at a carnival. They spent a total of $30 to buy a total of 22 packets of wafers of the two varieties.
Part A: Write a system of equations that can be solved to find the number of packets of strawberry wafers and the number of packets of chocolate wafers that Devon and his friends bought at the carnival. Define the variables used in the equations. (5 points)

Part B: How many packets of chocolate wafers and strawberry wafers did they buy? Explain how you got the answer and why you selected a particular method to get the answer. (5 points)

Answer 1

PART A
s = the number of packets of strawberry wafers ;
c = the number of packets of chocolate wafers ;
3 × s + 1 × c = 30 ;
s + c = 22 ;

PART B

The method of solving "by substitution" works by solving one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the other equation, "substituting" for the chosen variable and solving for the other. Then you back-solve for the first variable.

c = 30 - 3s;
s + ( 30 - 3s ) = 22;
30 - 2s = 22;
30 - 22 = 2s;
8 = 2s;
s = 4 ;
c = 30 - 12 ;
c = 18 ;