Rs. x invested at 8% simple interest per annum for 5 years yields the same interest as that on Rs. y invested at 7.5% simple interest per annum for 6years. Find x : y.
A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series. XIIIII, IXIIII, IIXIII, IIIXII,IIIIXI, ?