Chad is a door to door vacuum salesmen. His weekly salary, S(v)\displaystyle {S}{\left({v}\right)}, is given by the linear function S(v)=300+210v\displaystyle {S}{\left({v}\right)}={300}+{210}{v}, where v\displaystyle {v} is the number of vacuums sold. Identify the slope, and explain the meaning of the slope.