Ivan is a door to door vacuum salesman. His weekly salary S(v)\displaystyle {S}{\left({v}\right)} is given by the linear function S(v)=450+145v\displaystyle {S}{\left({v}\right)}={450}+{145}{v}, where v\displaystyle {v} is the number of vacuums sold. Identify the slope, and explain the meaning of the slope.