I know the answer but I don't know how to find the proper u-sub for it. I'm told I need to use U-sub for all the integrals. Here is where I end up
$$\int (1-\sec^2(\theta))\,d\theta -\int \tan^2(\theta)\sec^2(\theta)\,d\theta$$
My natural u-sub should be $\tan x$ since $dx$ would be $\sec^2$ but I don't know what to do about the other parts. Can I just u sub one section of the integral?