Question

Solve fr x:3x+4y=85; 6x+7y=20​

Answer 1

Given:

3x+4y=85—–(1)

6x+7y=20——-(2)

Multiplying equation (1) by 2 we get,

6x + 8y= 170 ——(3)

Solving equation (2) and (3) we get

6x + 8y= 170

6x+7y=20

(-)____________

y= 150

Substitutng y in equation (1) we get

3x + 4(150)=85

3x + 600=85

3x= – 515

x= -515 / 3

x=171.66

Hence x=171.66 and y= 150

Answer 2

Simplifying

3x + 4y + 6x + 7y = 85 + 20

Reorder the terms:

3x + 6x + 4y + 7y = 85 + 20

Combine like terms: 3x + 6x = 9x

9x + 4y + 7y = 85 + 20

Combine like terms: 4y + 7y = 11y

9x + 11y = 85 + 20

Combine like terms: 85 + 20 = 105

9x + 11y = 105

Solving

9x + 11y = 105

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-11y' to each side of the equation.

9x + 11y + -11y = 105 + -11y

Combine like terms: 11y + -11y = 0

9x + 0 = 105 + -11y

9x = 105 + -11y

Divide each side by '9'.

x = 11.66666667 + -1.222222222y

Simplifying

x = 11.66666667 + -1.222222222y