Question

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A restaurant has a total of 48 tables. There are three types of tables. Each small table seats 2
people. Each medium-sized table seats 5 people and each large table seats 12 people. A total
of 235 customers are seated when all the seats are taken up. There are 7 large tables. How
many medium-sized tables are there?

Answer 1

assumption method

7×12 = 84
235-84 = 151
48-7 = 41

assume all 41 tables r small
41×2 = 82
151-82 = 69
each → M-S = 5-2 = 3

69÷3 = 23 (Ans)

Answer 2

number of small tables --- x
number of large tables = 7
number of medium tables = 41-x
(check: x + 7 + 41-x = 48)

2x + 5(41-x) + 12*7 = 235
2x + 205 - 5x + 84 =235
-3x = -54
x = 18

so 18 small tables,
23 medium tables
7 large tables