Question

Find the value of $y$ by solving simultaneous equations.
$x+y=29$ and $x+2y=12$

• A. $-17$
• B. $12$
• C. $46$
• D. $75$

Answer 1

The correct option is A $-17$

Let $x+y=29$............(1)

and $x+2y=12$...........(2)

Multiple the (1) by $2$

$\Rightarrow 2x+2y=58$........(3)

Subtract (1) by (2), we get

$\Rightarrow x=46$

Substitute the value of $x$ in (1), we get

$\Rightarrow 46+y=29$

$\Rightarrow y=29-46$

$\Rightarrow y=-17$