$\frac{ 2 }{ 3 }{a}^{-2}{b}^{-1} \times \left( -18 \right){a}^{-3}b$
Multiplying an odd number of negative terms makes the product negative$-\frac{ 2 }{ 3 }{a}^{-2}{b}^{-1} \times 18{a}^{-3}b$
Cancel out the greatest common factor $3$$-2{a}^{-2}{b}^{-1} \times 6{a}^{-3}b$
Calculate the product$-12{a}^{-5}$
Express with a positive exponent using ${a}^{-n}=\frac{ 1 }{ {a}^{n} }$$-12 \times \frac{ 1 }{ {a}^{5} }$
Calculate the product$-\frac{ 12 }{ {a}^{5} }$