Question

Find the value of $x$, if $3-\frac{8}{7}x=\frac{9}{21}x+4$.

• A. $\frac{11}{7}$
• B. $\frac{-7}{11}$
• C. $\frac{7}{11}$
• D. $\frac{-11}{7}$

Answer 1

The correct option is B $\frac{-7}{11}$

Given, $3-\frac{8}{7}x=\frac{9}{21}x+4$.

Transposing $x$ terms to one side, we get,

$\Rightarrow -\frac{8}{7}x-\frac{9}{21}x=4-3$

$\Rightarrow -\frac{8}{7}x-\frac{9}{21}x=1$

$\Rightarrow \frac{-8\left(3\right)x-9x}{21}=1$ ...[Taking L.C.M.]

$\Rightarrow \frac{-24x-9x}{21}=1$

$\Rightarrow \frac{-33x}{21}=1$.

Multiplying by $21$ on both sides, we get,

$\Rightarrow -33x=21$

$\Rightarrow x=-\frac{21}{33}$

$\therefore$ $x=-\frac{7}{11}$.

Hence, option $B$ is correct.