An airline allows each passenger 42 kilogram of luggage. Carl has to lower the weight of his suitcase by 25% to stay within the limit. How much did the suitcase originally weigh

42 kg are allowed,

Carl has to lower by 25% to have 42 kg, so 42 kg will be 100%-25%=75% compare to what he has now.

42 kg - 75%

x kg - 100%

x=42*100/75=42*25*4/25*3=168/3=56 kg

56 kg is the original weigh of the suitcase