Find n(A) for the set
A= {1/2,-1/2,2/3,-2/3,3/4,-3/4,...,19/ 20,-19/20

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

Factor the polynomial, if possible. if the polynomial cannot be factored, write prime. 9n^3 + 27n^2 – 25n – 75

Simplify the algebraic expression 8y-2(y+4)