Sumdog-maths

Im playing a game called sum dog.I have to answer the questions then I grab a cake and fed the monsters. But when it starts to grow bigger or fatter they start to explode and thats how you win.I had to answer different types of questions to answer. I thought it was easy to play this

because I play sum dog all the time. I came 2nd in this game because I just didn't know a the answer.