5/20 can also be represented as 25/100 or 25%. The can be done by multiplying the top and bottom both by 5 and then dividing our numerator (25) by our denominator(100) to get the %.
The set with the strongest linear association is the top left
He buys 30 bottles which each costs 3 dollars. So 30 times 3 means he pays 90 dollars. Plus the 25 dollar handling fee which is 115. However the competing supplier is 4 dollars every bottle for the pint bottle. So if he bought 30 times 4 he would pay 120. That is without the handling money. So thats why he should stay with his