Please be a little more specific on what you want to ask.
I can be of some help.

Now, multiply both sides by 6 and you get.....
df+10=6g
now, subtract 10 on both sides and you get.....
df=6g-10
now divide both sides by d to get f by itself and you get........
The answer to the question is a
This is
{HH, TT, TH, HT} where H = head and T = tail