Answer:
Here we do not know the number of persons that will attend the party, but suppose that it is the number A, where A is a whole number.
For each of the A persons invited to the party, Tanisha needs to use 1/4 pound of ground beef to make a hamburger.
Then we need A times 1/4 pounds of ground beef.
The total ground beef needed is: A*(1/4) pounds = A/4 pounds.