Final answer:
After defining the number of pizza slices as 'p' and the number of burritos as 'b', the equations p = 2b - 20 and 2.50p + 3b = 358 were created and solved to find that 82 pizza slices were sold.
Step-by-step explanation:
The question asks for writing a system of equations and solving it to determine how many pizza slices and burritos were sold, given the prices of each and the total sales. The variables can be defined as follows: let p be the number of pizza slices sold, and b be the number of burritos sold.
Part a: System of Equations
The first equation represents the relationship between the number of pizza slices and burritos sold:
p = 2b - 20
The second equation represents the total sales from both items:
2.50p + 3b = 358
Part b: Solving the System
Substitute the first equation into the second:
2.50(2b - 20) + 3b = 358
5b - 50 + 3b = 358
8b - 50 = 358
8b = 408
b = 51
Now, substituting back to find p:
p = 2(51) - 20
p = 102 - 20
p = 82
Therefore, 82 pizza slices were sold.