Question

If (a, b) satisfies the given system of equations

$\{\begin{array}{c}5y-x=1\\ 4x-10y=6\end{array}$

then $a+b$ equals to

• A. $4$
• B. $5$
• C. $\frac{20}{3}$
• D. $2$

Answer 1

Answer: (B)

$5$

$\Rightarrow 5y-x=1$.........(1)

$\Rightarrow 4x-10y=6$........(2)

Multiply the (1) by $4$

$\Rightarrow 20y-4x=4$........(3)

Subtract the (3) and (2), we get

$\Rightarrow 10y=10$

$\Rightarrow y=\frac{10}{10}=1$

Substitute the value of $y=1$ in (1)

$\Rightarrow 5\times 1-x=1$

$\Rightarrow -x=1-5$

$\Rightarrow x=4$

Let $a=x$ and $b=y$, then

$\Rightarrow a+b=4+1=5$