you can add -10m and -13m but you can't add -10m and 2m^4 becuase the powers aren't the same so
when adding the like terms look at the: powers, (x^3 adds with x^3) placehloder letter (x adds with x and y adds with y and so on)
-10m+2m^4-13m-20m^4 powers: m^1 and M^4 placeholders: all m
add -10m-13m+2m^4-20m^4 -23m-18m^4
second one: when multiplying exponents, you add with like so if you multipliy x^2yz^3 times x^4y^2z^2 thne you would get x^6y^3z^5 when multiply with coeficients 2x^2yz^3 times 4x^4y^2z^2=8x^6y^3z^5 so using associative property a(bc)=(ab)c 2/3 times p^4 times y^3 times y^4 times s^5 times 6 times p^2 times s^3 group like terms
(2/3 times 6) times (p^4 times p^2) times (y^3 times y^4) times (s^5 times s^3) (4) times (p^6) times (y^7) times (s^8) 4p^6y^7s^8
