If Jeanette served 3/4 of a pizza to her friends, she has 1/4 of the pizza left.
To find out how many friends visited Jeanette, we can divide the amount of pizza she served (3/4) by the amount of pizza each friend was given (1/4):
(3/4) ÷ (1/4) = (3/4) x (4/1) = 3
So, Jeanette served 3/4 of a pizza to 3 friends.