we can ad like terms basically
x^2 can be added to 2x^2 but not 3 or 2x^4
so we have
(x^3+x^2)+(2x^3-5x^2)
using associative and commutative property
remove the parenthaseese
x^3+x^2+2x^3-5x^2
and move them around so group the like terms
1x^3+2x^3+1x^2-5x^2
add
3x^3-4x^2
tada
