This is telling you that a line that cross the coordinates (5,y) and (7,-9) has a slope of -4.

To compute the slope, we use the formula rise over run.  The rise is (y -(-9)) and the run is (5-7).  Therefore, the slope formula is (y-(-9))/(5-7)=-4.  Now we solve for y.

1.  (y-(-9))/(5-7)=-4

2.  Simplify...(y+9)/-2=-4

3.  Multiply both sides by -2...y+9=8

4.  Subtract 9 from both sides...and we get the answer -1.

5.  Check the work by substituting -1 in the formula.

(-1+9)/(5-7)=-4

This verifies that the answer is y=-1.

Hello Treena,

For solving this question you need to use the slope formula. m = (y₂ - y₁)/(x₂ - x₁)

Given to you are the coordinates of (x₁, y₁) and (x₂, y₂) and also the slope m.

x₁ = 5; y₁ = y; x₂ = 7, y₂ = -9 and m = -4

Substitute these values in the slope formula and solve for the variable y. You'll get the answer.

If you need further help, let us know.