Given the sequence: 4.5, 5.75, 7, 8.25, Find the common difference

An object in geometry with no width, length or height is a(n):

Afactory buys 10% of its components from suppliers b and the rest from supplier c. it is known that 6% of the components it buys are faulty. of the components brought from suppliers a,9% are faulty and of the components bought from suppliers b, 3% are faulty. find the percentage of components bought from supplier c that are faulty.

Need solving this 2nd limit problem.