$$=\frac{1}{5}\times\frac{a^{5}}{a^{2}}\times\frac{b^{3}}{b^{7}}\times\frac{c^{4}}{c}$$ $$=\frac{1}{5}\times a^{3}\times \frac{1}{b^{4}}\times c^{3}$$ $$=\frac{a^{3}c^{3}}{5b^{4}}$$