Jordan has a jar of quarters. when he has 60 quarters in the jar, the jar weighs 52 ounces. when there are 125 quarters in the jar, the jar weighs 65 ounces. what is the weight of the empty jar?

Let the weight of the empty jar be J.
Let the weight of a quarter be Q.
J + 125Q = 65 (1)
J + 60Q = 52 (2)
Subtracting equation (2) from equation (1), we get:
65Q = 13/65 = 1/5 ounce.
Plugging the weight of a quarter into equation (1), we get:
J + 25 = 65
J = 40
The weight of the empty jar is 40 ounces.