The problem states that $M$ is 150% of $N$. We need to find what percentage $N$ is of $M+N$.

1. Problem Description

The problem states that $M$ is 150% of $N$. We need to find what percentage $N$ is of $M+N$.

2. Solution Steps

First, we can express the given information as an equation:

$M = 150\% \times N$

$M = \frac{150}{100} \times N$

$M = \frac{3}{2}N$

Next, we need to find the value of $M+N$:

$M+N = \frac{3}{2}N + N = \frac{3}{2}N + \frac{2}{2}N = \frac{5}{2}N$

Now, we need to determine what percentage $N$ is of $M+N$:

Percentage $= \frac{N}{M+N} \times 100\%$

Percentage $= \frac{N}{\frac{5}{2}N} \times 100\%$

Percentage $= \frac{1}{\frac{5}{2}} \times 100\%$

Percentage $= \frac{2}{5} \times 100\%$

Percentage $= 0.4 \times 100\%$

Percentage $= 40\%$

3. Final Answer

40%