This is because 57 - 13 = 44. 44 divided by 4 = 11. This means that in 11 minutes Karen will have a 57 liter tank. But she could keep going, but the least number of minutes would be 11 minutes, to get to 57 liters.
I hope this helps! Please mark me Brainliest if it did! Thank you and have a nice day!