Question

If $\frac{15x}{9}-4=\frac{6x}{15}$, then the numerical value of $(6x-21)$ is

• A. $\frac{-117}{57}$
• B. $\frac{57}{117}$
• C. $\frac{-57}{117}$
• D. $\frac{117}{57}$

Answer 1

Answer: (A)

$\frac{-117}{57}$

Given, $\frac{15x}{9}-4=\frac{6x}{15}$

Transpose $x$ terms to one side

$\Rightarrow \frac{15x}{9}-\frac{6x}{15}=4$

L.C.M. of $9$ & $15$ is $45$.

$\Rightarrow \frac{75x-18x}{45}=4$

$\Rightarrow 57x=180$

$\Rightarrow x=\frac{180}{57}$

Therefore, value of $6x-21$ is

$=6\left(\frac{180}{57}\right)-21$

$=\frac{-117}{57}$