1. **State the problem:** We start with 15 wind turbines and add 1 turbine each month. We need to complete the table for 12, 24, and 48 months and write an expression for the number of turbines after $t$ months. 2. **Identify the formula:** The number of turbines after $t$ months is the initial number plus the number added each month times $t$. 3. **Write the expression:** $$\text{Number of turbines} = 15 + 1 \times t = 15 + t$$ 4. **Calculate the values for the table:** - For $t=12$ months: $$15 + 12 = 27$$ - For $t=24$ months: $$15 + 24 = 39$$ - For $t=48$ months: $$15 + 48 = 63$$ 5. **Complete the table:** | Time Adding Turbines (months) | Number of Turbines | |-------------------------------|--------------------| | 12 | 27 | | 24 | 39 | | 48 | 63 | **Final answer:** The expression for the number of turbines after $t$ months is $$15 + t$$.