Pedro's dog had two puppies. At 8 weeks old, the puppies weighed 2 kg and 1,875 g. What was the difference in the masses of the puppies in grams?

First lets change the weights in kilograms to grams so is easier to compare:

2kg = 2000 g

that is because 1 kg equals 1000 grams. So we can compare now:

2000 - 1875 = 125 g

therefore the difference in the masses of the puppies is 125 g