The mistake you are referring to is not clear in the statement.
It is a statement which only describe the weighs of Elsa's and Carson's pumpkins.
Elsa's pumpkin weighs 7/8 Pounds, while Carson's pumpkin weights 3/4 Pounds.
Step-by-step explanation:
Given that Elsa's pumpkin is 2/4 * 1/4 pound heavier than Carson's pumpkin, and Elsa thinks that Carson's pumpkin must weigh 3/4 pound.
Simplifying the weigh of her own pumpkin,
Elsa: 2/4 * 1/4 = 2/16 = 1/8 Pounds
Carson: 3/4 Pounds
Elsa's weigh should then be
3/4 + 1/8 = 7/8 Pounds.
