Q: Anna used four baking trays to bake cupcakes. Each tray has 20 cupcakes and each cupcake was then sold for $2. If only 3/5 of the cupcakes were sold and the rest were kept, how much did Anna earn from it?
A: Anna baked 4 x 20 = 80 cupcakes. She sold 80 x 3 / 5 = 48 cupcakes. Thus, she earned 48 x $2 = $96 from it. The answer is 96.

Q: Bert has a garden shop. He buys his products in a warehouse and sells them for $10 more in his shop. From each sale, he has to pay 10% of the value in tax. One day a client came to his shop and bought a barrel for $90. How Much money did Bert make on this sale?
A: First, we need to know how much Bert paid for the barrel in the warehouse, and that is 90 - 10 = $80. The tax from the sale stands at 10 / 100 * 90 = $9. That means Bert earned 90 - 9 - 80 = $1 on the sale. The answer is 1.

Q: The novel that everyone is reading for English class has half as many pages as their history book. Their science book has 4 times the amount of pages as their novel. If the history book has 300 pages, how many pages does their science book have?
A:
Their novel is half as long as their 300 - page history book so it is 300 / 2 = 150 pages. Their science book has 4 times the amount of pages as their novel, which is 150 pages, so their science book has 4 * 150 = 600 pages. The answer is 600.