Word Problems by Mau, Lala and Bee

1. There is a basket filled with frogs. A student gets the basket and tries to play a prank on the rest of the students. He goes to a classroom and places 3 frogs in it. Then, he goes to the second classroom and places 3 more frogs than he did in the previous classroom. In the third classroom he places 3 more than in the second, and so on until he puts in the 15th and last classroom 45 frogs. What is the total amount of frogs in all the classes?
2. Susana goes to the store and buys one chocolate bar. She ate it and love it so much that she went back to the store and bought 4 chocolate bars. Then, she went back to the store and bought 16 chocolate bars. If she went 16 times to the store, how many chocolate bars did she buy?