Hello Kelly,
Let P = number of pies the club made.
4(5) + 5P = 60
Where 4(5) represents the 4 pies the cafeteria contributed cut into 5 pieces each, 5P represents the pies the club made cut into 5 pieces each and 60 represents the total number of pieces of pie available to sell.
20 + 5P = 60
Subtract 20 from each side
5P = 40
Divide both sides by 5
P = 8
The club baked 8 pies.