In one coffee shop, the round table can seat 9 customers and the oval table can seat 3 customers. During dinner time, all the tables in the coffee shop were occupied. The number of each type of tables in the coffee shop is more than 3 and less than 9. If there were 81 customers, find
(a) the number of oval tables
(b) the number of round tables
Oval tables |
Number of customers around oval tables |
Round tables |
Number of customers around round tables |
Total number of customers |
4 |
4 x 3 = 12 |
4 |
4 x 9 = 36 |
12 + 36 = 48 (x) |
5 |
5 x 3 = 15 |
6 |
6 x 9 = 54 |
15 + 54 = 69 (x) |
6 |
6 x 3 = 18 |
7 |
7 x 9 = 63 |
18 + 63 = 81 (✓) |
(a)
Number of oval tables = 6
(b)
Number of round tables = 7
Answer(s): (a) 6; (b) 7