[tex]6.a) \frac{x \times 3x}{y \times {y}^{2} } = \frac{3 {x}^{2} }{ {y}^{3} } \\ b) \frac{10 {x}^{3} {y}^{2} }{(y - 1)(y + 1)} = \frac{10 {x}^{3} {y}^{2} }{ {y}^{2} - 1 } [/tex]
[tex]7.a) \frac{33}{40} \times \frac{10}{3} = \frac{11}{4} \\ b) - \frac{25}{32} \times \frac{8}{5} = - \frac{5}{4} [/tex]
