1. Statement of the problem: An IV releases 11 milliliters of medication every 3 minutes. An IV bag had 220 milliliters remaining after 180 minutes. 2. Model selection: This is a constant-rate linear situation so volume as a function of time $V(t)$ can be modeled by the linear equation $$V(t)=V_0+rt$$. Here $V_0$ is the initial volume and $r$ is the rate in milliliters per minute. 3. Compute the rate: The bag loses 11 milliliters every 3 minutes, so the rate is $r=-\frac{11}{3}$ milliliters per minute. 4. Apply the known condition: Substitute $t=180$ and $V(180)=220$ into the model to find $V_0$. 5. Intermediate work: $$220=V_0-\frac{11}{3}\cdot180$$. 6. Simplify: Compute $\frac{11}{3}\cdot180=11\cdot60=660$. 7. Solve for the initial volume: $$V_0=220+660=880$$. 8. Final equation: The volume as a function of time in minutes is $$V(t)=880-\frac{11}{3}t$$. 9. Extra result: The bag becomes empty when $V(t)=0$ so $$0=880-\frac{11}{3}t$$ which gives $$t=240$$ minutes. 10. Plain summary: The IV bag started with 880 milliliters, decreases by 11 milliliters every 3 minutes, and empties at 240 minutes.