Question:
What number should be subtracted from $\frac{3}{7}$ to get $\frac{5}{4} ?$
Solution:
Let, $x$ be subtracted.
$\therefore \frac{3}{7}-x=\frac{5}{4}$
$\Rightarrow x=\frac{3}{7}-\frac{5}{4}$
$\Rightarrow x=\frac{12}{28}-\frac{35}{28}$
$\Rightarrow x=\frac{12-35}{28}=\frac{-23}{28}$