[tex]s = 3r + 42[/tex]
s is the number of seats
r is the row number
3 because they increase by that each row
+42 because the starting row has 42
A
[tex]s = 3r + 42 \\ s = 3(25) + 42 \\ s = 75 + 42 \\ s = 117[/tex]
B
[tex]s = 3r + 42 \\ 90 = 3r + 42 \\ 90 - 42 = 3r \\ 48 \div 3 = 3r \div 3 \\ 16 = r[/tex]
