There are 40 tables in a library, with 30% of them seating 4 people. The tables remaining only seat 22 people. How many seats are there in the library?

Let 'x' represent the number of seats in the library.

30% of 40 tables is 0.30*40 = 12 tables.

The number of remaining tables is 40 - 12 = 28 tables.

0.30*40*4 + 28*22 = x

x = 664 seats

There are 664 seats in the library.