I think it would be 4x^2 and 3x^3 because they both have the same "x". Because you can't add, for example, 5x + 7z, they aren't alike. That's why you have to choose like terms, for example, 5x+ 5x= 10x.
For the bubble numbers put the second box in there, and for the chart put the first box.
Y=45x should be the correct answer.
