The box weighs 120 pounds and she's going to use half of it to make applesauce so she'll use 120 / 2 = 60 pounds for applesauce. The box weighs 120 pounds and she'll use 60 pounds for applesauce so that leaves 120 - 60 = 60 pounds of apples. She has 60 pounds of apples and she needs 4 pounds to make a pie so she can make 60 / 4 = 15 pies.
The answer: 15
Reverse engineering the question: Sandra has a box of apples that weighs 120 pounds. She's going to use half the weight in apples to make applesauce. The rest will be used to make apple pies. She needs 4 pounds of apples per pie. How many pies will she be able to make?

His sister is 10 * 2 = 20 years old. Their age difference is 20 - 10 = 10 years. Therefore when he is 50 she will be 50 + 10 = 60 years old.
The answer: 60
Reverse engineering the question: John is 10 years old. His sister is twice his age. When he is 50 years old, how old will his sister be?

He plays video games for 4 / 2 = 2 hours a day. He watches TV for 4 * 7 = 28 hours a week. He plays video games for 3 * 2 = 6 hours. So in total he spends 6 + 28 = 34 hours on those activities.
The answer: 34
Reverse engineering the question: Mike watches TV for 4 hours every day. On the days he plays video games he plays for half as long as he watches TV. If he plays video games 3 days a week how long does he spend watching TV and playing video games?

The amount paid to the teacher per day is 5 periods * $5 / period = $25 per day. The amount paid for 24 days is $25 / day * 24 days = $600. The total amount for 6 months is $600 * 6 = $3600.
The answer: 3600
Reverse engineering the question:
A teacher teaches 5 periods a day and works 24 days a month. He is paid $5 per period. if he has been working for 6 months now how much has he earned in total?