Question

Walter and Brian each have a CD collection.

The number of CDs in Walter's collection can be represented by x.

The number of CDs in Brian's collection is 3 times the number in Walter's collection.

The total number of CDs in both collections is 144.

What is x, the number of CDs in Walter's collection?

Answer 1

Let's denote the number of CDs in Walter's collection as \( x \). According to the problem, the number of CDs in Brian's collection is 3 times that of Walter's, which can be represented as \( 3x \).

The total number of CDs in both collections is given as 144. Therefore, we can set up the following equation:

\[
x + 3x = 144
\]

This simplifies to:

\[
4x = 144
\]

Now, we can solve for \( x \) by dividing both sides of the equation by 4:

\[
x = \frac{144}{4} = 36
\]

Therefore, the number of CDs in Walter's collection is:

\[
\boxed{36}
\]

To verify, we calculate the number of CDs in Brian's collection:

\[
3x = 3 \times 36 = 108
\]

Adding both collections together:

\[
x + 3x = 36 + 108 = 144
\]

This confirms that the calculation is correct. Thus, Walter has \( 36 \) CDs.