Final answer:
To find the number of lemon tarts sold, set up equations using the information given and solve for the unknown variable 'x'.
Step-by-step explanation:
To solve this problem, we can set up equations to represent the information given. Let's call the number of lemon tarts sold 'x'. From the information given, we can create the following equations:
Maple pecan pies sold: x/2 + 15
Brownie pops sold: (2/3)(x/2 + 15)
Total pieces sold: x + x/2 + 15 + (2/3)(x/2 + 15) = 223
Simplifying the equation, we get:
3x + x/2 + 45 = 669
6x + x + 90 = 1338
7x = 1248
x = 178
Therefore, the number of lemon tarts sold is 178.