Volume = Length*Width*Height. I guess the only confusing thing in this problem is that all 3 are given in different units. Let's convert them into the same unit.
Length = 55 Km = 55000 m = 5500000 cm
Width = 0.016 km = 16 m = 1600 cm
Height = 0.00035 = 0.35 m = 35 cm
Now if you want to express the volume in cubic metres, it is (55000*16*0.35) = 308000 cubic meters.
You can try it yourself for the other 2 (cubic km and cubic cm).
:)