Question

The sum of two numbers is 12 and their difference is 4 what are the two numbers?

Answer 1

Solution:-

:- Let

First No. be :- x

Second No. be :- y

According to question

=> x + y = 12 ..........(i) eq

=> x - y = 4 ..........(ii) eq

Now using substitution method

=> Add (i)eq and (ii)eq

=> x + y + x - y = 4 + 12

=> 2x = 16

=> x = 16 / 2

=> x = 8

Now put the value of x on (i)st eq

=> x + y = 12

:- x = 8

=> 8 + y = 12

=> y = 12 - 8

=> y = 4

So value of x = 8 and y = 4

Answer 2

• the 2 numbers is 8, 4

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$First \: \: no. \: \: be \: \: x \\ \\ Second \: \: no. \: be \: \: y$

a/q

$\implies \: x + y = 12 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: (i)$

$\implies \: x - y = 4 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: (ii)$

Now using substitution method

$\implies \: add \: > (i) \: and \: (ii)$

$\implies \: x + y + x - y = 4 + 12$

$\implies \: 2x = 16 \\ \\ \implies \: x = \frac{16}{2} \\ \\ \implies \: x = 8$

Now put the value of x on (i)

$\implies \: x + y = 12 \\ \\ = > x = 8 \\ \\ \implies \: 8 + y = 12 \\ \\ \implies \: y = 12 - 8$

$\huge \blue {\: \implies \: y \: = 4 }$