your answer is not right, number 9 have stick below, you need one more stick to do 9 from 4, you put stick on top, but also need to put below to make 9 from 4, i posted answer you can see that the right answer is : 9 + 3 - 4 = 8, where 9 is made from 8 removing one match, that is correct 9! My wife do this in 3 minutes)