helicopter 1 costing 11 million
leaving 36 million which would be enough for another 12 helicopters at 3 million each.

so 13 helicopters in all for your 47 million outlay

if the helicopters were being sold for 5.5 million each

we can take it case by case

one helicopter costs 11 million and sold for 5.5 million – total – 5.5 million

two helicopters costing at (11+3=14) million and sold for 11 million = a loss of 3 million

three helicopters costing (11+ 2×3= 17)million and sold for 3×5.5 million IE 16.5 million so producing a loss of half a million

4 helicopters costing (11 + 3×3 = 20 million) and sold for 4 x 5.5 million = 22 million and hence a PROFIT of 2 million

so the answer is 4 helicopters to make a profit

alternatively (not sure if we need to take the overall 47 million into account) we can list it as follows

47/5.5 gives us a minimum of 8 needed to recoup our monies entirely with the remaining 5 helicopters giving us pure profit