Find the slope using 2x-y=4

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?

Table which ratio is equivalent to 3: 7? 6: 7 3: 21 24: 56 15: 30

Kayaks rent for $35 per day. which expression can you use to find the cost in dollars of renting 3 kayaks for a day?