Question

Find the solution by substitution method
2x+y=21
3x+5y =49

Answer 1

Answer:-

Given:

2x + y = 21 -- equation (1)

3x + 5y = 49 -- equation (2)

From equation (1),

→ 2x + y = 21

→ y = 21 - 2x

Putting the value of y in equation (2) we get,

→ 3x + 5(21 - 2x) = 49

→ 3x + 105 - 10x = 49

→ 105 - 7x = 49

→ - 7x = 49 - 105

→ - 7x = - 56

→ x = (- 56)/(- 7)

→ x = 8

Substitute the value of x in equation (1)

→ 2x + y = 21

→ 2(8) + y = 21

→ y + 16 = 21

→ y = 21 - 16

→ y = 5

Hence, the values of x and y are 8 , 5.

Answer 2

$\huge{\bold{\star{\fcolorbox{black}{lightgreen}{ANSWER}}}}⋆$

• The value of x = 8
• The value of y = 5

$\huge{\bold{\star{\fcolorbox{black}{lightgreen}{Explanation}}}}⋆$

$\blue{\bold{\underline{\underline{Given}}}}$

2x + y = 21 -------------- (i)

3x + 5y = 49 ------------(ii)

$\blue{\bold{\underline{\underline{From \: equation \: (i)}}}}$

2x + y = 21

=> y = 21 - 2x

$\blue{\bold{\underline{\underline{Putting \: the \: value \: of \: y \: in \: equation \: (ii)}}}}$

3x + 5 (21 - 2x) = 49

=> 3x + 105 - 10x = 49

=> 105 - 7x = 49

=> -7x = 49 - 105

=> -7x = -56

=> x = (-56)/(-7)

=> x = 8

$\blue{\bold{\underline{\underline{Substitute \: the \: value \: of \: x \: in \: equation \: (i)}}}}$

2x + y = 21

=> 2(8) + y = 21

=> 16 + y = 21

=> y = 21 - 16

=> y = 5

Hence,

The value of x = 8.

The value of y = 5.