Sumo wrestlers in Japan are well known for their dedication, discipline, and very large bodies. A young sumo wrestler has decided he wants to gain a lot of weight as soon as possible by eating a special high-calorie and high-protein diet. After 4 months on this diet his mass is 100 kilograms and after 14 months his mass is 160 kilograms. Let's assume that the sumo wrestler's mass changes at a constant rate while he is on this special diet. What was the wrestler's initial mass in kilograms when he began his diet?

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