At a lunch function, ⁷₁₀ of the guests were men and the rest were women. Some men then left the lunch function and the remaining number of men were ³₅ of the guests. 57 men then joined the lunch function. The number of guests in the end was 17 more than the number of guests at first. How many guests were there at first?

	Men	Women	Total
Before	7x2 = 14 u	3x2 = 6 u	10x2 = 20 u
Change 1	- ?
After 1	3x3 = 9 u	2x3 = 6 u
Change 2	+ 57
After 2	9 u + 57	6 u	15 u + 57

The number of women remains unchanged.  Make the number of women the same.  LCM of 3 and 2 is 6.

The number of guests in the end was 17 more than the number of guests at first.
If 17 guests are added to the number of guests at first, the number of guests in the end and at first will be the same.

20 u + 17 = 15 u + 57
20 u - 15 u = 57 - 17
5 u = 40

1 u = 40 ÷ 5 = 8

Number of guests at first
= 20 u
= 20 x 8
= 160

Answer(s): 160