Question

Solve -3+7y=5x+2y when x=-5

Answer 1

`y=-(22)/(5)`

Explanation:

`-3+7y=5x+2y\\x=-5`

Replace:

`-3+7y=5(-5)+2y\\-3+7y=-25+2y`

Subtract -2y

`-3+7y-2y=-25`

Add 3

`7y-2y=-25+3`

Combine like terms;

`5y=-22`

Divide by 5.

`y=-(22)/(5)`

Proof

`For x=-5, y=-(22)/(5)`

`-3+7y=5x+2y`

`-3+7(-(22)/(5) )=5(-5)+2(-(22)/(5) )`

`-3-(154)/(5)=-25-(44)/(5)`

To make it easier to solve, add 154/5

`-3=-25-(44)/(5)+(154)/(5)`

Now add 25

`-3+25=-(44)/(5)+(154)/(5)`

Combine like terms;

`22=(110)/(5) \\22=22`

Answer 2

y = -22/5

Explanation:

-3+7y=5x+2y

Subtract 2y from each side

-3+7y-2y=5x+2y-2y

-3 +5y = 5x

Add 5 to each side

5y = 5x+3

Divide each side by 5

y = 5x/5 +3/5

y = x +3/5

Let x = -5

y = -5 + 3/5

y = -25/5 +3/5

y = -22/5