(1-cota) (1+cota) (1+cot^2a)

Combined megan and kelly worked 60 hours. kelly worked twice as many hours as megan. how many hours did they each worked?

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Prove that 16^4-2^13-4^5 is divisible by 11.