Three of the thirty computers are out of service. what percent of the computers are working?

Ineed to know the answer to this algebra question.

Find a third-degree polynomial equation with rational coefficients that has roots -2 and 6+i

Choose the domain & range of the relation shown in the graph: domain: -1, 0, 1, 2, 3 range: -3, -1, 0, 3 domain: -3, -1, 0, 3 range: -3, -1, 0, 3 domain: -3, -1, 0, 3 range: -1, 0, 1, 2, 3 domain: 3, 1, 0, 3 range: -1, 0, 1, 2, 3