When you divide fractions you really just multiply one of them by the reciprocal of the other. You can find the reciprocal by flipping the fraction upside down, so the reciprocal of [tex] \frac{-12}{20} [/tex] will be [tex] \frac{20}{-12} [/tex]. Now, multiply the first fraction by that reciprocal.
[tex] \frac{-72}{45} [/tex] ÷ [tex] \frac{-12}{20} [/tex] Change the second fraction to its reciprocal
[tex] \frac{-72}{45} [/tex] x [tex] \frac{20}{-12} [/tex] Multiply (-72 x 20 and 45 x -12)
[tex] \frac{-1440}{-540} [/tex] Simplify both by their GCF, 180
[tex] \frac{-8}{-3} [/tex] The negatives cancel out
[tex] \frac{8}{3} [/tex] 3 goes into 8 two times, with 2 left over
[tex]2 \frac{2}{3} [/tex]
