Let x be the weight of the cantaloupe. We know that the watermelons weight four pounds more, this means that the weight of the watermelons can be express as:

Now, the weight of two cantaloupes can be express as 2x while the weight of five watermelons can be express as 5(x+4); hence the total weight is express as:

and we know that this is equal to 27 pounds, hence we have the equation:

To determine the weight of each of them we solve the equation above for x:

Therefore each cantaloupe weighs one pound and each watermelon weighs 5 pounds.