Which polynomial correctly combines the like terms and expresses the given polynomial in standard form?

9xy3 – 4y4 – 10x2y2 + x3y + 3x4 + 2x2y2 – 9y4
–13y4 + 3x4 – 8x2y2 + x3y + 9xy3
–13y4 + x3y – 8x2y2 + 9xy3 + 3x4
3x4 – 8x2y2 + x3y + 9xy3 – 13y4
3x4 + x3y – 8x2y2 + 9xy3 – 13y4

The line containing the midpoints of the legs of right triangle abc where a(-5,5), b(1, 1), and c(3, 4) are the vertices.

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

Yuto and hila attempted to solve the same inequality. their work is shown below. which statement is true about the work shown above? yuto is correct because he isolated the variable correctly and reversed the inequality symbol. yuto is incorrect because he should not have reversed the inequality symbol. hila is correct because she isolated the variable correctly and reversed the inequality symbol. hila is incorrect because she should not have reversed the inequality symbol.