The simple interest on a sum of money is 16/25 of the principal. The number of years is equal to the rate of interest per annum. What is the rate (in percentage) of interest per annum?
A man leaves from his home for work on his motorcycle. He goes 5 km South, then turn to his left and travels 6 km, then turns South and travels 13 km then turns West and travels 6 km to reach his office. Where is his office with reference to his home?