I want to sit down

Step 1: There are 10 arms in the room and only people have arms, so there must be 5 people.

Step 2: There are 18 legs in the room, 4 of which belong to the table and 10 of which belong to the 5 people. Therefore, there are only 4 legs unaccounted for which must belong to one chair.

Step 3: Since there are 5 people, 4 more chairs are needed in order for everyone to be seated.

I know the obvious solution is 4 but technically a chair can have 3 legs (I've both seen and sat in one before) so the problem would technically need to be revised to say that each chair has 4 legs

10 arms => 10/2 = 5 people 5 people x 2 legs = 10 legs 18 legs - 10 legs = 8 legs 8 legs includes 4 legs of table and 4 legs of chair. so currently there is one chair. need 4 more chairs to have 5 chair in the room

Using the information given:

"There are 10 arms in the room and 18 legs." $\displaystyle P = \frac{10}{2} = 5; C = \frac{18 - 4 - 10}{4} = 1$

If there are 5 people and 1 chair, $\boxed{4}$ more chairs are needed so everyone gets to sit down.

Therefore, the answer is 4 .