Write the polynomials in standard form: (15–7xy^2)–(y^3–y^2x–15)

-y³ -6y²x +30

When parentheses are eliminated and the y variable placed first in each term, the expression simplifies to ...

... 15 -7y²x -y³ +y²x +15

Arranging like terms together, we have ...

... -y³ +y²x(-7 +1) +(15 +15)

... -y³ -6y²x +30

The two different 3rd-degree terms can be expressed in either order. I have chosen to list the term with the largest exponent first. The expression could also be written with the same-degree terms in "lexicographical order", meaning the expression would be written ...

... -6xy² -y³ +30

ruth is 6 years old

step-by-step explanation:

6 + 24 = 30,   so 6/30 = .2  

if you do 1/5 it also equals .2, so that is the answer.