13: Since f(1)=10, the sequence must start with 10. We have only one sequence starting with 10, and indeed it verifies f(n+1)=f(n)-2, i.e. the next term is 2 less than the previous one.
14: If y varies directly with x, then there is a constant of variation k such that
[tex]\dfrac{y}{x}=k \iff y=kx[/tex]
In your case, F varies directly with m, with a constant of variation of 32.2, so we have
[tex]F=32.2m[/tex]
