-5/12 ÷ 15/36

1. Rewrite division as multiplication by the reciprocal: $$- \frac{5}{12} \times \frac{36}{15}$$

2. Multiply the fractions: $$- \frac{5 \times 36}{12 \times 15}$$

3. Simplify: $$- \frac{180}{180} = -1$$