Recall that the slope-intercept form of the line equation is of the form y=mx+b, where m is the slope and b is the y-intercept.
To transform the equation 10=-2y-x into the slope-intercept form we should apply algebraic operations so we isolate the y on one side of the equation.
Let's add x on both sides, we get

Now, lets divide by -2 on both sides, we get

we see that this now has the slope-intercept form, where the slope is m=(-1/2) and b=-5