Barbara is 6 years old. Andy is double Barbara's age. How old will Andy be in 4 years?

The sum of two numbers is 16. One number is 4 more than 5. What is the other number?

Charlotte has to do all the even numbered problems up to 15 in her math book. She decided to do 5 more problems after that. How many problems did Charlotte do altogether?

There were four cards with a number written on each. The numbers were 5, 9, 3, and 7. Jenna took out one of the cards. The sum of the remaining numbers was 17. Which number did Jenna take?

Jeff is on the middle step of a ladder. There are the same number of steps above him as below him. Jeff goes down 2 steps, up 5 steps, then down 9 steps. He is now on the bottom step of the ladder. How many steps does the ladder have?