I need help with the whole page. Its geometry proofs. (When will I need to know this in my life )

Iq scores for adults age 20 to 34 years are normally distributed according to n(120, 20). in what range does the middle 68% of people in this group score on the test?

Select the correct answer from the drop-down menu. subtracting 3xy^2 from 8xy^2 gives the same result as the expression. [tex]3xy ^{2} - 8xy ^{2} [/tex][tex] { - 7xy}^{2} - {2xy}^{2} [/tex][tex] {7xy}^{2} - {2xy}^{2} [/tex]

Is this a polynomial function? i need to know asap