The intersecting chords theorem or just The chord theorem is a statement in elementary geometry that describes a relation of the four line segments created by two intersecting chords within a circle. It states that the products of the lengths of the line segments on each chord are equal. Each chord is cut into two segments at the point of where they intersect. One chord is cut into two line segments A and B. The other into the segments C and D. This theorem states that A×B is always equal to C×D no matter where the chords are.
If you round each amount to the nearest ten you get $130.00, $60.00, and 50.00. When you add all of those together you get an estimated amount of $240.