They decided to hold the party in their backyard. They have 12 sets of tables and each set has 14 chairs. There are also 6 chairs extra. How many chairs do they have for the guests?
Let's denote the number of sets of tables by n. Then the number of chairs in each set is 14. 

The total number of chairs is 

n*14. 

The number of extra chairs is 6. 

Therefore the total number of chairs for the guests is 

n*14+6. 

Therefore the answer (numeric) is: 

12*14+6 = 168+6 = 174