Okay, I will give you this coupon if you successfully solve this riddle (yes, this is my homework, but why not). You know f(x) is derivative of some F(x) function. You need to find F(x) of this function: Example of F(x) and its derivative f(x): (If you are winner, I need to ask your Steam ID or Steam Nickname, remember it)

https://www.symbolab.com/solver/step-by-step/\int \sin\left(3x+\frac{\pi}{6}\right)\text{dx} no need to give me anything, I like helping people with math

Glad to hear it: that website is really useful for math calculations, and if shows you the steps to take underneath as well. Kinda like Wolfram Alpha, but easier to use imo