Question

The first row I️n the auditorium has 42 seats.each row after the first has 3 more seats than the row before I️t

A: find the number of seats I️n row 25

B:which row had 90 seats ?

Answer 1

A. 117 seats
B. row 16

Answer 2

$s = 3r + 42$
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
$s = 3r + 42 \\ s = 3(25) + 42 \\ s = 75 + 42 \\ s = 117$
B

$s = 3r + 42 \\ 90 = 3r + 42 \\ 90 - 42 = 3r \\ 48 \div 3 = 3r \div 3 \\ 16 = r$