Question

X+y=7;x+2y=11
Solve by substitution
steps must.​

Answer 1

• 
  `\boxed{ \tt \red{ x = 3}}`
• 
  `\boxed{ \tt \pink {y = 4}}`

Explanation:

Step: Solve x+y=7 for x:

x+y=7

x+y+−y=7+−y(Add -y to both sides)

x=−y+7

Step: Substitute−y+7 for x in x+2y=11:

x+2y=11

−y+7+2y=11

y+7=11(Simplify both sides of the equation)

y+7+−7=11+−7(Add -7 to both sides)

y=4

Step: Substitute 4 for y in x=−y+7:

x=−y+7

x=−4+7

x=3(Simplify both sides of the equation)

Answer:

`\boxed{\sf x = 3 \: and \: y = 4}`

Answer 2

Explanation:

x + y = 7 ------------(I)

y = 7 - x ------------(II)

x + 2y = 11 --------------(III)

Substitute y = 7 - x in equation (III)

x + 2 * (7 -x) = 11

x + 2*7 - 2*x = 11

x + 14 - 2x = 11

x - 2x + 14 = 11

- x + 14 = 11

Subtract 14 from both side

-x = 11 - 14

-x = -3

Multiply both sides by (-1)

x = 3

Substitute x=3 in equation (II)

y = 7 - 3

y = 4