This is a tough one. 100 Hours Hmm...would have been much easier to think of it has 20 hours or something. I will think of it has 20 hours total, and then multiply the values by 5 at the end
Content Writing: 8 Hours x 5 = 40 Hours
Link Building/Marketing 12 Hours x 5 = 60 Hours
This is just my case, I find writing easier for me, so I take a little less time. The other stuff would take me a bit longer. I feel it usually depends on the ability of each person however, everyone can succeed!