Why do paleontologists use radioactive dating and carbon dating to tell the age of a fossil

The difference between two numbers is 15. when twice the smaller number is subtracted from three times the larger number, the difference is 58.what is the larger number?

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

What is the orbital period of a spacecraft in a low orbit near the surface of mars? the radius of mars is 3.4×106m.