1. **State the problem:** We need to find the cost of Maggie's phone bill if she uses 165 minutes in October, given the cost per minute and a known bill for 120 minutes. 2. **Given information:** - Cost per minute $m = 0.30$ - Maggie's bill for 120 minutes is $51$ - The point-slope form of the equation is given as $$y - 51 = 0.30(x - 120)$$ where $x$ is minutes and $y$ is cost. 3. **Use the point-slope formula:** The point-slope form of a line is $$y - y_1 = m(x - x_1)$$ where $(x_1, y_1)$ is a point on the line and $m$ is the slope. 4. **Substitute $x = 165$ to find $y$:** $$y - 51 = 0.30(165 - 120)$$ 5. **Calculate inside the parentheses:** $$165 - 120 = 45$$ 6. **Multiply slope by difference:** $$0.30 \times 45 = 13.5$$ 7. **Add 51 to both sides to solve for $y$:** $$y - 51 = 13.5$$ $$y = 13.5 + 51$$ 8. **Calculate the total cost:** $$y = 64.5$$ **Final answer:** Maggie's bill for 165 minutes is $64.5$.