Answer:
Set up an equation (you can use the distance formula as an equation). The distance formula is Y2-Y1/X2-X1.
2-(-4)/x-5=-3
6/x-5=-3
Multiply both sides by x-5.
6=-3(x-5)
Distribute the -3 to the terms in the parentheses.
6=-3x+15
Subtract 15.
-9=-3x
Divide both sides by -3.
3=x
So, the missing number of the coordinate is 3.
:)