Final answer:
John's weight can be represented by the expression t + 13, where t is Tom's weight.
Step-by-step explanation:
To represent John's weight, we start with Tom's weight, which is represented by the variable 't' pounds. John weighs 13 pounds more than Tom, so we can add 13 to Tom's weight to find John's weight. Therefore, the expression that represents John's weight is t + 13.