## Thinking Mathematically (6th Edition)

The total number of proper subsets is $7$.
Represented with the roster method, the set looks like this: $\{3, 4, 5\}$ A set of $n$ elements has $2^n$ subsets. This set has 3 elements; therefore, it has $2^3=8$ subsets. However, we are asked for distinct subsets, so we have to take 1 from the result, as one of the subsets is going to be the set itself. The total number of proper subsets is $8-1=7$.