To list all subsets of the set $A = \{a, b, c, d\}$ that have 3 elements, we need to select 3 elements out of the 4 available elements in the set.

The number of ways to choose 3 elements from a set of 4 is given by the binomial coefficient $\binom{4}{3}$. This is equal to 4, which means there are 4 subsets of 3 elements.

The subsets of $A$ that have exactly 3 elements are:

1. $\{a, b, c\}$
2. $\{a, b, d\}$
3. $\{a, c, d\}$
4. $\{b, c, d\}$

These are all the possible subsets of size 3 from the set $A = \{a, b, c, d\}$.

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Would you like any further explanation or examples?

Here are some related questions:

1. How do you calculate the number of subsets of a set of any size?
2. How do you calculate the number of subsets of size $k$ from a set of $n$ elements?
3. What is the difference between a subset and a proper subset?
4. How can you list all subsets of a set with more elements?
5. How do you determine the power set of a set?

Tip: To find subsets of a set, think of each element as either being in or out of the subset. This gives you a systematic way to generate all subsets.