1. **State the problem:** We need to solve for $a$ in a factored form given $y=5$, $s=-2$, and $t=4$. 2. **Assume the factored form:** Typically, a factored form involving $a$, $s$, and $t$ might be $y = a(s)(t)$. 3. **Write the formula:** $$y = a \times s \times t$$ 4. **Substitute the known values:** $$5 = a \times (-2) \times 4$$ 5. **Simplify the right side:** $$5 = a \times (-8)$$ 6. **Solve for $a$ by dividing both sides by $-8$:** $$a = \frac{5}{-8}$$ 7. **Show cancellation explicitly:** $$a = \frac{\cancel{5}}{\cancel{-8}}$$ (no common factors to cancel, so fraction remains as is) 8. **Final answer:** $$a = -\frac{5}{8}$$ This means $a$ equals negative five eighths.