x = -20.5
First, we have to multiply each side by 5. This gets rid of the fraction. This leaves you with 2x - 9 = -50.
You want to get x alone on one side, so next you add nine to both sides.
2x = 41
Finally, divide both sides by 2
x = -20.5
To check this, substitute 20.5 for x in your original equation.
(2(-20.5) - 9)/5 = -10
(-41 - 9)/5 = -10
-50/5 = -10
-10 = -10
Both sides equal each other, so -20.5 is the right answer