## Algebra: A Combined Approach (4th Edition)

Using the formula T = 50 + $\frac{N - 40}{4}$, substitute the value given into the equation. 65 = 50 + $\frac{N - 40}{4}$ Solve for N: 15 = $\frac{N - 40}{4}$ 60 = N - 40 100 = N Interpret: 100 chirps per minute