The formula given in the problem is the condensed form. Although I think there is a missing term there to make it logical. Each carbon atom can bond to 4 atoms. So, if once atom has C only, it means that it is occupied by 4 subfunctions only. So, the condensed form should be: (ch3)3cch(oh)ch2ch2ch(ch3)2. The structural formula is shown in the picture. The longest chain contains 7 carbon atoms.