Between 1955 and 1956, Dayan and Shimon Peres negotiated a series of large weapons contracts with France. On 10 November 1955, an agreement was signed for the delivery of 100 AMX-13 tanks and assorted anti-tank weapons. On 24 June 1956, a $80 million deal was agreed involving 72 Dassault Mystère IV jets, 120 AMX-13 tanks, 40 Sherman tanks and 18 Obusier de 155 mm Modèle 50. The Mystere were in addition to 53 already on order. At the end of September 1956, a further 100 Sherman tanks, 300 half-tracks, and 300 6x6 trucks were added.
Question: How many more AMX-13 tanks than Sherman tanks did the agreement call for?
Answer: 80