The numbers in front of all the $$\mathtt{x^4}$$ terms can be added and the result written in front of $$\mathtt{x^4}$$. Similarly, the sum of the numbers in front of all the $$\mathbf{x^3}$$ terms become one number in front of $$\mathbf{x^3}$$. As usual, those numbers have a +/- sign which must be observed when you evaluate the sums.
The numbers in front of all the $$\mathtt{x^4}$$ terms can be added and the result written in front of $$\mathtt{x^4}$$. Similarly, the sum of the numbers in front of all the $$\mathbf{x^3}$$ terms become one number in front of $$\mathbf{x^3}$$. As usual, those numbers have a +/- sign which must be observed when you evaluate the sums.
