The easiest way to find the slope of a line given in standard form is to put it into slope-intercept form.
Slope-intercept form: y = mx + b
---m is the slope, b is the y-intercept
10x + 5y = 4
5y = -10x + 4
y = -2x + 4/5
The slope of the line is -2.
Hope this helps!
