Unknown number related questions in linear equations

Lessons

1. Two numbers have a sum of 24. Find the two numbers if the second number is 6 times the first one.
   
2. The sum of four times one number plus two times a second number is eight. The sum of three times the first number plus 5 times the second number is 24. Find the numbers.
   
3. Sarah is three times as old as her sister Jenny. In nine years the sum of their ages will be 26. How old are they now?