I am wondering how much will a 20% of the research grade affect my grade?

I now have a 84 percent on my test grade which worth 60% of the whole course. That's say if I have a 0 percent on of the research grade that worth 20 percent, how will it affects on my whole grade? How much grade I need to have for my participation grade which worth anothor 20% to get me at least 75% of total grade?