To add the two mixed numbers \(-1 \frac{3}{10}\) and \(2 \frac{1}{5}\), we can follow these steps:
- Convert the mixed numbers to improper fractions.
- Find a common denominator.
- Add the fractions.
- Convert back to a mixed number if necessary.
Step 1: Convert to Improper Fractions
\(-1 \frac{3}{10}\):
- The improper fraction can be calculated as: \[ -1 \frac{3}{10} = -\left(1 \times 10 + 3\right)/10 = -\frac{13}{10} \]
\(2 \frac{1}{5}\):
- The improper fraction can be calculated as: \[ 2 \frac{1}{5} = 2 \times 5 + 1/5 = \frac{11}{5} \]
Step 2: Find a Common Denominator
The denominators are \(10\) and \(5\). The least common denominator (LCD) is \(10\).
Convert \(\frac{11}{5}\) to a fraction with a denominator of \(10\): \[ \frac{11}{5} = \frac{11 \times 2}{5 \times 2} = \frac{22}{10} \]
Step 3: Add the Fractions
Now we can add the fractions: \[ -\frac{13}{10} + \frac{22}{10} = \frac{-13 + 22}{10} = \frac{9}{10} \]
Step 4: Convert Back to a Mixed Number
\(\frac{9}{10}\) is already a proper fraction and can be expressed as: \[ \frac{9}{10} = 0 \frac{9}{10} \] This is just \(0.9\) in decimal form.
Thus, the final result of \(-1 \frac{3}{10} + 2 \frac{1}{5}\) is: \[ \frac{9}{10} \] or equivalently in decimal format, \(0.9\).