Solve the all parts of given problem:
Problem: A system of 1287 particles, each of which is either an electron or a proton, has a net charge of -1.026×10-16 C.
Part I: How many electrons are in this system (exactly)?
Part II: What is the mass of this system (to three significant digits)?
Could someone please show me the work and explain how to get the answer for above problem.