How many seats are in the restaurant?

210.
If 25% of the tables seat 2 people, you would just multiply 60 by 0.25, to find the number of tables that seat 2. (60 * 0.25= 15) 

So now that you know 15 tables have two seats, you know that the remain 45 tables have 4 seats. Then just multiply the number of tables, by the number of chairs at each table, to get the total amount of chairs in the restaurant.

( 45 tables x 4 chairs @ each table =180
                                                             +      > = 210 :)
(15 tables x 2 chairs @ each table =   30