Simplify. - 10m+2m^4-13m-20m^4

(do i have to add the coefficients)

and

Simplify. (2/3 p^4 y^3) (y^4 s^5) (6p^2 s^3)

First one:

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