Solution:
Given:
[tex]\begin{gathered} T=50+\frac{N-40}{4} \\ \\ \text{where,} \\ T\text{ is the temperature in degre}e\text{ fahrenheit} \\ N\text{ is the number of chirps per minute} \end{gathered}[/tex]
when T = 55,
substituting T = 55 into the equation given,
[tex]\begin{gathered} T=50+\frac{N-40}{4} \\ 55=50+\frac{N-40}{4} \\ 55-50=\frac{N-40}{4} \\ 5=\frac{N-40}{4} \\ \text{Cross multiplying the equation,} \\ 5\times4=N-40 \\ 20=N-40 \\ \text{Collecting the like terms,} \\ 20+40=N \\ N=60 \end{gathered}[/tex]
Therefore, the number of chirps per minute (N) = 60.
