Agatha spends 15 + 25 = 40 dollars. Agatha had 40 + 20 = 60 dollars at first.
The answer: 60
Reverse engineering the question: Agatha has some money to spend on a new bike. She spends $15 on the frame, and $25 on the front wheel. If she has $20 left to spend on a seat and handlebar tape, how much money, in dollars, did she have at first?

Find the number of students who got their degree by multiplying: 804 students * 75% = 603 students. Then find the number of students who didn't pass their exams by subtracting this number from the total: 804 students - 603 students = 201 students.
The answer: 201
Reverse engineering the question: Out of 804 senior high school students, 75% passed their exams and so got their degree. The rest failed. How many didn't pass their exams?

Stephanie wants to get 5 each of each type of silverware for herself. 5 spoons + 5 butter knives + 5 steak knives + 5 forks = 20 pieces of silverware. She wants 10 extra of each type for guests, 10 x 4 = 40. She decides to purchase less of each type. She was originally purchasing 15 of each type. 15 spoons - 4 less spoons = 11 spoons. 15 butter knives - 4 less = 11. 15 steak knives - 5 = 10. 15 forks - 3 less forks = 12. Stephanie is going to purchase 11 spoons, 11 butter knives, 10 steak knives, and 12 forks. 11 + 11 + 10 + 12 = 44. Stephanie is going to purchase 44 pieces of silverware.
The answer: 44
Reverse engineering the question: Stephanie is moving into a new apartment. She needs to figure out how many pieces of silverware she should purchase. She needs spoons, butter knives, steak knives, and forks. For herself she figures 5 of each would be sufficient. But in case she has guests, she wants to have 10 extra pieces of each type. Then she realizes that if everything is clean at the same time, that she will have too many of everything and not enough room to fit them in her kitchen silverware drawer. So she decides to purchase 4 fewer spoons, 4 fewer butter knives, 5 fewer steak knives, and 3 fewer forks. How many pieces total of all the silverware is Stephanie going to buy?

Each minute last 60 seconds, so that means for the fries to be fully cooked Bill needs to cook them for 5 * 60 = 300 seconds. Since Bill had the fries in the oven for 45 seconds so far, that means they need to stay in the oven for another 300 - 45 = 255 seconds.
The answer: 255
Reverse engineering the question:
Bill put his french fries in the oven after it finished heating. The recommended time was 5 minutes for them to be fully cooked. He put them in for 45 seconds. How many seconds remained?