Math Word Problems/Riddles?

Tell your friend to enter six 9’s in the calculator and divide by 7. Then pick any number between 1 and 6 and multiply the calculator result by it. Then tell your friend that if he or she tells you the first digit you will tell all the others! How does it work?

At the farmers market three adjacent farmers Christian, Jose and Maria are selling comparable apples and always keep their prices the same. That is, if one changes their price then all change their price to be the same. At the end of the day Christian sold 100 apples, Jose 150 and Marla 200, yet they each took in the same amount of money which was $20. How is this possible and how much did they charge per apple? Note: there is more than one solution.

A car drives from NY to Montauk and averages 40 mi/h. On the return trip the car averages only 30 mi/h. If the distance traveled each way is 120 miles, what is the average speed for the entire trip? Note: It is not 35 mi/h.