Answer:
10 - x
Step-by-step explanation:
You have x red velvet flavored muffins.
5 chocolate flavored.
y vanilla flavored (let y be the amount of vanilla flavored muffins there are).
You know that the total amount of muffins is 15. In other words, the sum of the amounts of all 3 different muffin types is 15.
We can construct an equation using this knowledge and solve for y.
[tex]x + 5 + y = 15 \text{ //}-5\\x + 5 + y - 5 = 15 - 5\\x + y = 10 \text{ //}-x\\x + y - x = 10 - x\\y = 10 - x[/tex]
There are 10 - x vanilla flavored muffins.