[tex] \frac{12 {a}^{4} {b}^{6} }{5 {c}^{7} } \div \frac{4 {a}^{3 {b}^{5} } }{10 {c}^{3} } \times \frac{7 {c}^{5} }{6 {a}^{2}b } [/tex]

[tex] \frac{12 {a}^{4} {b}^{6} }{5 {c}^{7} } \times \frac{10 {c}^{3} }{4 {a}^{3} {b}^{5} } \times \frac{7 {c}^{5} }{6 {a}^{2}b } [/tex]

[tex] \frac{3ab}{ {c}^{4} } \times 2 \times \frac{7 {c}^{5} }{6 {a}^{2}b } [/tex]

[tex]2 \times \frac{7c}{2a} [/tex]

[tex] \frac{7c}{a} [/tex]