The ratio of length to width would change slightly, before adding on to the dimensions, the ratio is 6 : 2.5 with the added dimensions, the ratio would change to 8 : 4.5 with simple math you can see that 2.5 is less then half of 6 while 4.5 is more then half of 8
He made 3.75 gallons. There was 1/10 remaining, meaning each tenth was 6 cups. The entire thing is 10 tenths so you do 6(10) to get 60 cups. After converting to gallons by doing 60÷26, you get 3.75.