Please Square the Following Monomials

11. (-4m3)2

12. (-5y4)2

13. (9ab)2

14. (10x2y2)2

15. (-12cd3)2

16. (-15r2s4)2

17. (3/4a)2

18. (5/3c)2

19. (-7/8m)2

20. (-4/5x2)2