1. **Problem statement:** Given the system of equations: $$n + h = 12$$ $$s - h = 6$$ and the value of $h = -72$. 2. **Formula and rules:** We use substitution or elimination to solve systems of linear equations. 3. **Step 1:** Substitute $h = -72$ into the first equation: $$n + (-72) = 12$$ $$n - 72 = 12$$ 4. **Step 2:** Solve for $n$: $$n = 12 + 72 = 84$$ 5. **Step 3:** Substitute $h = -72$ into the second equation: $$s - (-72) = 6$$ $$s + 72 = 6$$ 6. **Step 4:** Solve for $s$: $$s = 6 - 72 = -66$$ 7. **Final answer:** $$n = 84, \quad h = -72, \quad s = -66$$