1. The problem asks us to write a formula for the total number of doughnuts Tom buys, denoted by $T$, given he buys $B$ bags and $C$ cartons of doughnuts. 2. To express $T$ in terms of $B$ and $C$, we need to know how many doughnuts each bag and each carton contains. However, since the question does not specify this, we can express $T$ in a general form: $$T = b \times B + c \times C$$ where $b$ is the number of doughnuts in each bag and $c$ is the number of doughnuts in each carton. 3. This formula shows that the total doughnuts is the sum of doughnuts from all bags plus doughnuts from all cartons. Since the counts per bag ($b$) and carton ($c$) are not given, this is the most general formula we can write. Final answer: $$T = bB + cC$$