Question 1066675
.
Although your wording is far from perfect, I can guess what you want:


|x - (-7.5)| = 2.5.


Or, which is the same, 


|x + 7.5| = 2.5.


{{{graph( 330, 330, -12.5, 2.5, -3.5, 10.5,
          abs(x+7.5), 2.5
)}}}


Plots y = |x + 7.5| (red) and y = 2.5 (green)