calculate the interest produced by the following three capitals, placed at interest simple, at an annual rate of 12%:

a) 1st capital: 35000 placed from April 5 to July 15 of the same year;

b) 2nd capital: 40000 placed from April 1 to August 25 of the same year;

 c) 3rd capital: 50000 placed from April 9 to October 19 of the same year.