What sum will amount to Rs-580 at 8% per annum at the end of 2year?

8% is an abbreviation for 0.08 x.

8% for one year means simple interest.

I + 0.08 x I = 1.08I where I means Initial Amount.

For 2 years, 1.08I becomes the new initial amount for the second year.

580 = (1.08)^2 x I The rule is you can do any valid operation on both sides of an equation and it will still be equal. Divide by (1.08)^2.

I = 580/1.1664 = 497.26