A theater has 40 seats in the first row 42 seats in the second row 44 seats in the third world how many seats are in the 20th row

It seems to be increasing by two each time. So, a simple equation would work.

Let y = total seats

Let x = row number

y = 38 + 2x. Substitute 20 for x

y = 38 + 2 (20) solve for the total.

y = 78.

There are 78 seats in the 20th row