the first thing you need to do is set up the equation. from the question, you can set up this equation
1800 = 2x - 1500
from this, you need to subtract 1500 from both sides
then, you get:
3300 = 2x
to find x, divide both sides of the equation by two:
1800 = 2x - 1500
--------------------------
2
from this, you get that x = 1650
ANSWER: x = 1650