14. Factoring Polynomials

What is the greatest common factor of the following lists of numbers?

$42,70,98$

What is the greatest common factor of the following lists of numbers?

$19,57$

What is the greatest common factor of the following sets of monomials?

$6x,9x^2,15x^3$

What is the greatest common factor of the following sets of monomials?

$30m^3{n}^2,45m^2{n}^4,75m^4{n}^3$