The total number of seats is 675, and it is given by the number of rows multiplied by the number of seats in each row, then let's call x the number of rows:
[tex]\begin{gathered} 675=x\times(3x) \\ 675=3x^2 \\ \frac{675}{3}=x^2 \\ 225=x^2 \\ x=\sqrt[]{225} \\ x=15 \end{gathered}[/tex]
Then, there are 15 rows, and the number of seats in each row is 15*3=45 seats
