I can rewrite this condition as an inequality: $7.5 < \frac{N}{3} < 8$. To get rid of the fraction, I can multiply everything by 3: $22.5 < N < 24$. Now I need to find a whole number that satisfies this inequality. I can see that 23 is the only whole number in this interval, so $N = 23$. 
A whole number, $N$, is chosen so that $\frac{N}{3}$ is strictly between 7.5 and 8. What is the value of $N$ ?