3. Yes the cost of each item is proportional because in each pack each t-shirt cost $2.33. You can check that by dividing the amount of money each pack cost by the amount of shirts in each pack. For example the pack of 3 is $7, so 7/3 = $2.33. The pack of 5 cost $11.65, so 11.65/5 = $2.33. And the pack of 7 cost $16.31, so 16.31/7 = $2.33
4) Yes, it is proportional because each x is being squared or multiplied by it’s self.