a)
[tex] \frac{7 {x}^{2} }{5} \times \frac{2}{7x} = \frac{2x}{5} [/tex]
b)
[tex] \frac{3}{2x} \times \frac{11 {x}^{2} }{3} = \frac{11x}{2} [/tex]
c)
[tex] \frac{8x}{3} \div \frac{4 {x}^{3} }{9} = \frac{8x}{3} \times \frac{9}{4 {x}^{3} } = \frac{6}{ {x}^{2} } [/tex]
d)
[tex] \frac{10 {x}^{3} }{7} \div \frac{5x}{4} = \frac{10 {x}^{3} }{7} \times \frac{4}{5x} = \frac{2 {x}^{2} \times 4}{7} = \frac{8 {x}^{2} }{7} [/tex]