Logical Puzzles

23. There is a number, the second digit of which is smaller than its first digit by 4, and if the number was divided by the digit’s sum, the quotient would be 7. Can you find the number?
The number is 84.
24. Melinda and her father love puzzles. When Melinda’s cousin asked her how old she was she told her :“If I doubled my age and subtracted 1, it would be the same as my father’s age - and if you reverse the digits of his age, you get my age.” Can you work out their ages?
Jenny is 37, her father is 73.