Fluid Mechanics in SWCE

For Darcy-Weisbach flow with $n = 2$, a loop has net head loss $\sum r Q^2 = 12\text{ m}$ and denominator $2 \sum r |Q| = 60\text{ m}/(\text{m}^3/\text{s})$. The flow rate correction $\Delta Q = -\frac{12}{60}$ in $\text{m}^3/\text{s}$ is: