Could someone explain to me how to find out it sec, csc, or cot are undefined?

Which expression is equivalent to (4x^3*y^5)(3x^5*y)^2 \a) 24x^13*y^7b) 36x^13*y^7c) 36x^28*y^7d) 144x^16*y^12

Find all the values of x that make 0.1x + 0.25(102 - x) < 17.10 true.

3382-299=3383- ? fill in the blank?