To express the total number of mini pies Alvin can bake (y) based on the number of cups of sugar he buys (x), we can set up the equation as follows:
Initially, Alvin can bake 6 mini pies. For each additional cup of sugar he buys, he can bake 4 more mini pies. Therefore, the equation can be expressed as:
\[ y = 6 + 4x \]
where:
- \( y \) is the total number of mini pies,
- \( x \) is the number of additional cups of sugar he buys.
So, the final equation is:
\( y = 6 + 4x \)