There are 35 seats in the first row of the cinema hall, and in each next one there is one more than in the previous one.

There are 35 seats in the first row of the cinema hall, and in each next one there is one more than in the previous one. How many seats are there in the eighth row?

Consider the following arithmetic progression:

a (n) = a1 + (n – 1) * d.

a1 = 35 (seats).

d = 1.

And in this case n = 8.

Let’s substitute all values in the original formula.

a (8) = 35 + (8 – 1) * 1 = 35 + 7 = 42 (places).

Answer: there are 42 seats in the eighth row.