Question

Solve: 3x + 5y = 7
x + 2 y = 10​

Answer 1

We have,

• 3x + 5y = 7 .......(i)
• x + 2y = 10 .......(ii)

from eq.(ii)

x + 2y = 10

➪ x = 10 - 2y .......(iii)

now, substitute the value of x from (iii) in (i)

$\bold{: \implies \: 3(10 - 2y) + 5y = 7} \\ \\ \bold{ : \implies 30 - 6y + 5y = 7} \: \: \: \: \: \: \: \\ \\ \bold{: \implies \: - 6y + 5y = 7 - 30 } \: \: \: \\ \\ \bold{: \implies \cancel- y = \cancel - 23} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \bold{: \implies \boxed{ \bold{ y = 23 }}} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:$

now, substitute the value of y in (iii)

$\bold{: \implies \: x = 10 - 2(23) } \\ \\ \bold{ : \implies \: x = 10 - 46 } \: \: \: \: \: \: \\ \\ \bold{: \implies \: \boxed{ \bold{x = - 36 }}} \: \: \: \: \: \: \: \: \: \:$

hence, value of y is 23 and value of x is -36