Answer:
the answer is 5x^2+9x-18y
Explanation:
since 5x^2 does not have like terms, it is left alone. next, combine all of the x variables which are 7x and 2x to get 9x. that leaves you with the y values which are -8y and -10y to get -18y. when combining terms, always look for similar variables. remember, just because some value has the same variable doesn't mean it is necessarily the same. for example, you cannot combine x^2 and x because one has a power and the other does not. i hoped this helped.