Breaking down:
[tex] \frac{3}{15} = \frac{1}{5} [/tex]
[tex] {w}^{6} \div {w}^{2} = {w}^{4} [/tex]
[tex] {v}^{5} \div v = {v}^{4} [/tex]
Therefore,
[tex] \frac{3 {w}^{6} {v}^{5} }{15 {w}^{2}v } \\ = \frac{{w}^{4} {v}^{4} }{5}[/tex]
Hope this helps. - M