Answer:
18 muffins
Step-by-step explanation:
From the information given, you can write the following equations:
x+y=34 (1)
0.50x+0.75y=21 (2)
where x is the number of muffins and y is the number of bagels.
First, you can isolate x in (1):
x=34-y (3)
Then, you can replace (3) in (2):
0.50(34-y)+0.75y=21
17-0.5y+0.75y=21
0.25y=21-17
0.25y=4
y=4/0.25
y=16
Now you can replace the value of "y" in (3):
x=34-16
x=18
According to this, the answer is that you sold 18 muffins.