A person borrows some money for 8 years at a rate of simple interest. If the ratio of principal and total interest is 5 : 8, then what is the rate ( inpercentage) of interest?
In a college, the ratio of boys to girls is 29 : 33 respectively. When 142 more boys join the college, this ratio becomes 21 :19. How many more girls should join the college to make the number of boys and girls equal?