Answer :

In standard form, slope is always the negative of the x coefficient over the y coefficient.

If you dont want to have that memorized, you can use algebra to get the equation of the line into slope-intercept form (y=mx+b)

Set it equal to y

2x - 5y = 6
2x = 5y + 6
2x - 6 = 5y
(2/5)x - 6/5 = y
Now it is in slope intercept form. In slope intercept form, the coefficient multiplying with x is the slope of the line. Therefore, the slope equals 2/5.
2x - 5y = 6, 5y = 2x - 6, divide by 5 on both sides
y = (2/5)x - (6/5), 
sample equation is y = mx + c, here m is slope, 
so for equation y = (2/5)x - (6/5), 
m = 2/5 = slope.