Question

Find the unknown using an inverse operation:
$q+7=\frac{21}{4}$

Answer 1

$q+7=\frac{21}{4}$

taking denominator $4$, we get the above equation as,

$4q+28=21$

$4q=21-28$

$4q=-7$

Now taking inverse of $4$ and multiplying the above eqn by the inverse of $4$ ie $\frac{1}{4}$

$4\times \frac{1}{4}q=-7\times \frac{1}{4}$

$q=\frac{-7}{4}$