Find any intervals where the function f(x)=−(5x+5sin(x)),0≤x≤2π is increasing/decreasing.

You guys are awesome. Thanks!

is x in radians or degrees?

If x is in radians, then f(x) is decreasing from [0, π) and at (π, 2π], or 0≤x<π and π<x≤2π.

I think radians. If it's not then I can just do any conversions to degrees.

In degrees, it is just a constantly decreasing linear function, so x is in radians.

You're welcome

f(x)=−(5x+5sin(x)) = -5(x + sinx)

f'(x) = -5(1+cosx)
clearly f' < 0 for all x where cosx > -1. That is all real values except odd multiples of π.