Question

Solve the following pair of equations by method of substitution
$x+y=3$ and $2x+5y=12$

Answer 1

Given equations are

$x+y=3$ ....(1)

and $2x+5y=12$ ....(2)

Therefore, $x=3-y$ ....(3)

Substitute this value of $x$ in equation (2), we get

$2(3-y)+5y=12$

$\Rightarrow 6-2y+5y=12$

$\Rightarrow 6+3y=12$

$\Rightarrow 3y=6$

$\Rightarrow y=2$

Put this value in equation (3)

$x=3-y=3-2=1$

Therefore, solution is $x=1,y=2$.