28. 24 is divided into two parts such that 7 times the first part added in 5 time the second part makes 146. The first part is:

29. The sum of two numbers is 29 and the difference of their squares is 145. The difference between the number is

30. A certain number of two digits is three times the sum of its digits and if 45 be added to it, the digits are reversed. The number is: