Multiply :

- 3bx, - 5xy and - 7b³y²

-3bx $\times$ (-5xy) $\times$ (-7b³y²)

= -3 $\times$ (-5) $\times$ (-7) b⁽¹⁺³⁾x⁽¹⁺¹⁾y⁽¹⁺²⁾

= -105 b⁴x²y³

Hence, (- 3bx) $\times$ (- 5xy) $\times$ (- 7b³y²) = -105b⁴x²y³