Jill owns 1/3, her brother owns 1/4, and the third partner owns 5/12 of the pizza restaurant.
Jill owns 1/3 of the pizza restaurant, and her brother owns 1/4. To determine the fraction owned by the third partner, we need to find a common denominator for 3 and 4, which is 12.
Jill's share is equivalent to 4/12 (since 3 multiplied by 4 is 12), and her brother's share is equivalent to 3/12 (since 4 multiplied by 3 is 12). When combined, Jill and her brother own 7/12 of the restaurant.
To find the fraction owned by the third partner, subtract the total ownership of Jill and her brother from 1 (the whole). Thus, 1 - 7/12 equals 5/12. Therefore, the third partner owns 5/12 of the pizza restaurant.
In summary, Jill owns 4/12, her brother owns 3/12, and the third partner owns 5/12 of the pizza restaurant, making a total of 12/12 or the entire ownership.