Have to write a slope intercept form from this equation 2x + 1.50y = 15

The equation is in standard form. Standard form is in this formula:
Ax + By = C
To convert a standard form to slope intercept form you first move Ax to the other side of the equation by inverse operations.
2x + 1.50y = 15
-2x                -2x
1.50y = -2x + 15

You then divide B (From By) across the whole equation. (If you can't evenly divide make it a fraction) 
1.50y = -2x + 15
1.50         1.50
y = -2/1.50x + 10