Question
Evaluate: $-\frac{2}{3}-\left(\frac{-5}{7}\right)$
✓
Answer
$\begin{aligned} & -\frac{2}{3}-\left(\frac{-5}{7}\right) \\ & \Rightarrow-\frac{2}{3}+\frac{5}{7}\end{aligned}$
| 3 | 3,7 |
| 7 | 1,7 |
| 1,1 |
L.C.M. of 3 and $7=3 \times 7=21$
$ \begin{aligned} & \Rightarrow \frac{-2 \times 7}{3 \times 7}+\frac{5 \times 3}{7 \times 3} \\ & (\because \text { L.C.M. of } 3 \text { and } 7=21)
\end{aligned} $
$ =\frac{-14+15}{21}=\frac{1}{21} $
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