What if it is 10 millimeters

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

Michael is training for a marathon. in his first week he plans to run 8miles. what path should he take

Either enter an exact answer in terms of \piπ or use 3.143.14 for \piπ and enter your answer as a decimal.