Find the sum of the 5th terms of an arithmetic sequence whose fourth and fifth Terms are 13 and 15

Its due 1. what is the product of 1/2-1/4? write your answer in standard form.a) show your work.b) is the product of 1/2x-1/4 and 5x^2-2x+6 equal to product of 1/4x-1/2 and 5x^2-2x+6? explain your answer.