Final answer:
John's original weight before the decrease was 98.25 kilograms, calculated by adding his current weight of 85.75 kilograms to the amount he decreased by, which is 12.5 kilograms (12500 grams converted to kilograms).
Step-by-step explanation:
To determine John's original weight before the decrease, we simply need to add the decreased amount to his current weight. First, we convert the decreased amount from grams to kilograms since his current weight is given in kilograms. We know that 1 kilogram is equal to 1000 grams, so to convert 12500 grams to kilograms we divide it by 1000, giving us 12.5 kilograms.
Next, we add this value to John's current weight:
85.75 kg + 12.5 kg = 98.25 kg
Since the least precise measurement we are working with is the decreased amount (12.5 kg is precise to the tenths place), our final answer should be rounded to the tenths place as well. However, in this case, since both values are already to the tenths place, no additional rounding is needed, and the final answer remains 98.25 kg. Therefore, John's weight before the decrease was 98.25 kilograms.