based on what is given you have R=3h+3v and we need to solve for h
our goal is to get "h" by itself on one side of the equal sign and everything else on the other side. the first step would be to subtract 3v from both sides. now we have R-3v=3h
When a letter or "variable" is next to a number it means they are being multiplied. to undo multiplication we must divide. so to separate the 3 and the "h" we must divide by 3 and make sure to do this to both sides.
so now we have (R-3v)/3=H and that should be your answer
hope this helps