Question

solve by substitution method
X+y=18, x-y=4​

Answer 1

Answer:-

$\red{\bigstar}$$\large\boxed{\tt\purple{x = 11}}$

$\red{\bigstar}$$\large\boxed{\tt\purple{y = 7}}$

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• Given:-

• x + y = 18

• x - y = 4

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• To Find:-

• Value of x and y.

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• Solution:-

✴ $\sf x + y = 18 \dashrightarrow\bf\red{[eqn.i]}$

✴ $\sf x - y = 4 \dashrightarrow\bf\red{[eqn.ii]}$

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• Taking eqn.[i]:-

➪ $\sf x + y = 18$

➪ $\sf x = 18 - y \dashrightarrow\bf\red{[eqn.iii]}$

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• Substituting eqn.[iii] in eqn.[ii]:-

➪ $\sf x - y = 4$

➪ $\sf (18-y) - y = 4$

➪ $\sf 18 - y - y = 4$

➪ $\sf 18 - 2y = 4$

➪ $\sf - 2y = 4 - 18$

➪ $\sf - 2y = - 14$

➪ $\sf y = \dfrac{-14}{-2}$

★ $\large{\bf\pink{y = 7}}$

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• Substituting value of y in eqn.[i]:-

➪ $\sf x + y = 18$

➪ $\sf x + 7 = 18$

➪ $\sf x = 18 - 7$

★ $\large{\bf\pink{x = 11}}$

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Therefore, value of x = 11 and y = 7.

Answer 2

$\huge\bold{\gray{\sf{Answer:}}}$

Explanation:

Given :

X+y=18.......(1)

and x-y=4........(2)

To Find :

x and y values

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From Equation(1)

We find substitute for x and put into Equation2

$x + y = 18$

$x = 18 - y........(3)$

Put X's value into Equation2

$= > x - y = 4$

$= > (18 - y) - y = 4$

$= > 18 - 2y = 4$

$- 2y = 4 - 18$

$= > - 2y = - 14$

$y = \frac{ - 14}{ - 2} = 7$

$\bold{\boxed{\red{y = 7}}}$

Now ,put Y's value into Equation1

$x = 18 - y$

$x = 18 - 7 = 11$

$\bold{\boxed{\pink{x = 11}}}$

Check:-

$x + y = 11 + = 18$

$x - y = 11 - 7 = 4$