Answer
11 four-seated tables and 6 two-seated tables
Work Step by Step
t = # of two-seated tables
f = # of four-seated tables
Total number of tables = 17
t + f = 17
Each two-seated table has 2 customers
Each four-seated table has 4 customers
Total number of customers
2t + 4f = 56
t + f = 17 can be written as t = 17 - f. Plug this into 2t + 4f = 56
2(17 - f) + 4f = 56
34 - 2f + 4f = 56
34 + 2f = 56
2f = 22
f = 11
There are 11 four-seated tables
Plug f into t + f = 17
t + 11 = 17
t = 6
There are 6 two-seated tables
