It should be 100 multiply 1.15.
A minor point of style first .. the calculation as stated (FF x 1.15) results in FF + VR. VR, on its own, is 0.15 x FF. I'm sure that's what you meant but it does make it difficult for the examiner to give you marks if you are needlessly careless in your answers ...
Now, presuming that you do not intend to carry any margin fuel (ie fuel which is additional to statutory requirements), do you think that such a plan, as you have proposed, necessarily is wise ? There may be situations arise where you leave yourself short of fuel for the alternate ...
For instance
(a) you don't have any other available alternates, you take minimum fuel as you have described, and then use, say, all of your planned VR on the first leg. After all, that's what it's for ... to cover problems on the sector.
(b) now, Sod's law at work again, when you get to the original destination, the wx has gone below minimums and you are committed to head off to the alternate (in this case even without attempting an approach and landing because you don't have any spare fuel to cover that contingency and you sure can't risk burning into what will come out of your FR at the divert aerodrome).
(c) where were you proposing to get some VR for the divert sector ? All you have in the tanks is divert FF + FR + unusable.
Sure, in an emergency, you can borrow into FR a little and, for the majority of aircraft, unusable actually provides an (unknown to you) amount of fuel which actually is usable due to the way in which unusable is determined. However, to do such things routinely is not a good way to make it to retirement and a nice superannuation nest egg.
One needs to be VERY cautious with fuel in the tanks on departure. There are more than enough problems which can arise to frighten the flightcrew without their fuel planning needlessly adding to their woes.
A good story pertinent to this consideration relates to an MMA F28 near mishap, 40-odd years ago in the west. The following link is to the Captain's relating the tale to a, no doubt, enthralled audience -
There have been more than a few unplanned situations arise where the final diversion has had the aircraft land with fumes only left in the tank. I can recall one such on the 727 years ago where mis-forecast MEL wx ended up putting the aircraft into CBR with engines running down during the landing and taxy in ...
It was only several years ago that two airline flights found themselves very uncomfortably embarrassed at MQL. The ATSB report makes for essential reading, I suggest -
www.atsb.gov.au/publications/investigati...13/aair/ao-2013-100/
Be wary out there .. there be dragons. Sometimes you can do what you have proposed ... sometimes, though, it might not be wise. One fairly common strategy, where appropriate, is to carry a PNR for the first sector .. with the hopeful (and, usually, reasonable) expectation that you will make enough fuel prior to the PNR to replan for the remainder of the initial sector AND the alternate requirements.
You really do need to think about the what ifs before you commit ...
) , will I be able to use this or other copies of my own in the exam?