The number of DVD's sold at Fry's Electronics in a month was 920 and the number of DVD's sold decreased by 12 per month. The number of Blu-ray discs sold at Fry's Electronics in the same month was 502 and the number of Blu-ray discs sold increased by 26 per month. Write a system of equations to model th situation. If this trend continues, in how many months will the number of DVD's sold each month equal the number of Blu-ray discs sold each month? How many each disc is sold in that month?