What should be added to `2/5` to get `-1`?

Answer

To find out what should be added to \( \frac{2}{5} \) to get \(-1\), we can set up the equation as follows:

Let \( x \) be the number that we need to add to \( \frac{2}{5} \). The equation can be written as:

\[ \frac{2}{5} + x = -1 \]

### Step 1: Rearranging the Equation
To isolate \( x \), we can subtract \( \frac{2}{5} \) from both sides of the equation:

\[ x = -1 - \frac{2}{5} \]

### Step 2: Finding a Common Denominator
To perform the subtraction, we need to express \(-1\) as a fraction with the same denominator as \( \frac{2}{5} \). The denominator of \( \frac{2}{5} \) is \( 5 \), so we can write \(-1\) as:

\[ -1 = -\frac{5}{5} \]

### Step 3: Performing the Subtraction
Now we can substitute \(-\frac{5}{5}\) into our equation:

\[ x = -\frac{5}{5} - \frac{2}{5} \]

Now, we can combine the fractions:

\[ x = -\frac{5 + 2}{5} = -\frac{7}{5} \]

### Step 4: Conclusion
Thus, the number that should be added to \( \frac{2}{5} \) to get \(-1\) is:

\[ x = -\frac{7}{5} \]

### Final Answer
The answer is \( -\frac{7}{5} \).

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