Hi guys, im having a little trouble with an excersie sheet i was given for homework, the whole page consists of questions like this one and if someone could explain just how one is done to me, id be able to finish it on my own

The questions go like this: Multiply out and collect like terms.

(1-2x+3x^2)(4-5x+6x^2)

im sorry if i sound stupid but i only know how to do 2 sets of values in each bracket and one value in each bracket is an x term... these ones are the next step up and i find them really difficult