Help in this one please

One of the inventors of integrated circuits observed that the number of transistors that fit on an integrated circuit will double every 24 months. what type of relationship most appropriately models this situation?

Find two numbers if their sum is 91 and the ratio is 6: 7?

Find the unit rate. enter your answer as a mixed number. a fertilizer covers 2/3 square foot in 1/2 hour.