In a supermarket, ⁷₁₁ of the customers were female. There were 54 more female customers. Within five minutes, some female customers left the supermarket. As a result, there were ⁶₇ as many male customers as female customers. How many female customers left the supermarket during the five minutes?
Number of female customers = 7 u
Total number of customers = 11 u

Number of male customers
= 11 u - 7 u
= 4 u

7 u - 4 u = 54
3 u = 54

1 u = 54 ÷ 3 = 18

Number of female customers at first
= 7 u
= 7 x 18
= 126

Number of male customers
= 4 u
= 4 x 18
= 72

The number of male customers remains unchanged.
6 p = 72

1 p = 72 ÷ 6 = 12

New number of female customers
= 7 p
= 7 x 12
= 84

Number of female customers who left
= 126 - 84
= 42

Answer(s): 42