Answer this question:A store marks a book 30% above the cost. But during a sale, a 10% discount was given. If the book costs $50, what is the percent profit?
The store made a $50 x 30 / 100 = $15 profit for selling it 30% above the cost. So, the book was sold for $50 + $15 = $65. During a sale, the book's selling price decreased by $65 x 10 / 100 = $6.50. So, the book was sold for $65 - $6.50 = $58.50. There was $58.50 - $50 = $8.50 profit after the discount. Therefore, the percent profit is $8.50 / $50 x 100% = 17%.
The answer is 17.

Answer this question:Mark and Peter dug ponds in their backyards. Mark's pond is 4 feet deeper than 3 times Peter's pond. If Mark's pond is 19 feet deep, what is the depth of Peter's pond?
Let's use p for the number of feet in Mark's pond. 3 * p + 4 = 19. 3 * p = 19 - 4 = 15. 3p = 15. p = 5.
The answer is 5.

Answer this question:Jenna catches an eel that's 1/3 as long as Bill's. If the combined length of their eels is 64 inches, how long is Jenna's eel?
Let j be the length of Jenna's eel and b be the length of Bill's eel. We know that b = 3j and b + j = 64. Substituting the first equation into the second equation, we get 3j + j = 64. Combining like terms, we get 4j = 64. Dividing both sides by 4, we get j = 16.
The answer is 16.

Answer this question:Johan has a ten-bedroom house with 8 walls in each room. He paints 3/5 of the rooms in the house green and paints the rest of the rooms with purple color. How many walls in the house did he paint purple?
Since Cristian's house has ten rooms, he painted 3 / 5 * 10 = 6 rooms with green color. The number of rooms he painted with purple is 10 - 6 = 4 rooms. Since each room in the house has eight walls, the number of walls painted purple is 8 * 4 = 32.
The answer is 32.