$$1) \frac{7a^{2}b^{3}}{9ax^{2}y}*\frac{18x^{2}c}{15ac^{4}}$$
$$2) \frac{21k^{2}p^{3}}{13mn^{2}}\div\frac{28p^{2}k^{3}}{39m^{2}n^{3}}$$
$$3) \frac{2x^{2}y}{3yz}\times\frac{5z^{2}x}{7xy^{2}}\div\frac{21x^{2}y^{3}z^{2}}{40xy^{2}z}$$
$$4) \frac{m^{2}}{8n}\times\frac{36p^{3}q^{2}}{81mn}\div\frac{15mpx^{5}}{27n^{2}x^{3}y}$$
$$5) \frac{14x^{2}-7x}{12x^{3}+24x^{2}}+\frac{2x-1}{x^{2}+2x}$$
$$6) \frac{a^{2}b^{2}+3ab}{4a^{2}-1}\div\frac{ab+3}{2a+1}$$
$$7) \frac{x^{2}-4a^{2}}{ax+2a^{2}}\times\frac{2a}{x-2a}$$
$$8) \frac{a^{2}-121}{a^{2}-4}\div\frac{a+11}{a+2}$$
$$9) \frac{16x^{2}-9a^{2}}{x^{2}-4}\times\frac{x-2}{4x-3a}$$
$$10) \frac{25x^{2}-9a^{2}}{x^{2}-4}\times\frac{x-2}{4x-3a}$$