1. **State the problem:** The PTA needs to raise 15000 from memberships. Each membership brings in 25. They already have 2500. We want to find how many memberships, $m$, are needed. 2. **Set up the equation:** Total money needed equals money already raised plus money from memberships. $$15000 = 2500 + 25m$$ 3. **Isolate $m$:** Subtract 2500 from both sides. $$15000 - 2500 = 25m$$ $$12500 = 25m$$ 4. **Solve for $m$:** Divide both sides by 25. $$\frac{12500}{\cancel{25}} = \frac{25m}{\cancel{25}}$$ $$500 = m$$ 5. **Answer:** The PTA needs 500 memberships to reach 15000 total. This means 500 new memberships must be sold to raise the required amount.