You would solve this by finding the slope. The wrestler would have started at month 0. The slope formula is y1-y2/x1-x2. We are going to use the first two numbers for the slope,
93.6-85.8/3-1.5 Then we simply the equation.
7.8/1.5
5.2
This means that each month and a half. He gains 5.2 kilograms. So, we would subtract this from the first number in our table. 85.8-5.2=80.6
The wrestler was 80.6 kilograms when he started his diet