Question

7x+5y=34 and 4x+3y=20 substitution method​

Answer 1

Step-by-step explanation:

solution

7x+5y=34

7x=34-5y ------- equ (1)

4x+3y=20

4(34-5y)+3y=20 from equ (1)

136-20y+3y=20

-17y=-116

17y=116

y=116/17

y=6.8

7x=34-5*6.8

7x=34

x=4.85

Answer 2

Answer:

The solution of the given equations is ( x, y ) = ( 2, 4 ).

Step-by-step-explanation:

The given linear equations are

7x + 5y = 34 - - - ( 1 ) &

4x + 3y = 20

⇒ 3y = 20 - 4x

⇒ y = ( 20 - 4x ) / 3 - - - ( 2 )

By substituting equation ( 2 ) in equation ( 1 ),

7x + 5y = 34 - - - ( 1 )

⇒ 7x + 5 [ ( 20 - 4x ) / 3 ] = 34

⇒ 7x + [ ( 100 - 20x ) / 3 ] = 34

⇒ [ 7x * 3 + ( 100 - 20x ) ] / 3 = 34

⇒ 21x + 100 - 20x = 34 * 3

⇒ 21x - 20x + 100 = ( 30 + 4 ) * 3

⇒ x + 100 = 90 + 12

⇒ x = 90 + 12 - 100

⇒ x = 90 - 100 + 12

⇒ x = - 10 + 12

⇒ x = 2

By substituting x = 2 in equation ( 2 ),

y = ( 20 - 4x ) / 3 - - - ( 2 )

⇒ y = ( 20 - 4 * 2 ) / 3

⇒ y = ( 20 - 8 ) / 3

⇒ y = 12 / 3

⇒ y = 4

∴ The solution of the given equations is ( x, y ) = ( 2, 4 ).