Answer:
He fails to sell that day 10 cottons.
Step-by-step explanation:
We are given that a cotton candy merchant earns 40 cents for each cotton sold, but if he cannot sell it he loses 50 cents.
One day when he made 120 cottons, he made a profit of 39 soles.
Let the number of cottons merchant is able to sold be 'x' and the number of cottons merchant is not able to sold be 'y'.
So, according to the question;
x + y = 120
x = 120 - y ---------------------- [Equation 1]
[tex]0.40x - 0.50y=39[/tex]
[tex]40x - 50y=3900[/tex]
[tex]40(120-y) - 50y=3900[/tex]
[tex]4800-40y - 50y=3900[/tex]
[tex]90y=4800-3900[/tex]
[tex]90 y = 900[/tex]
[tex]y=\frac{900}{90}=10[/tex]
This means that the merchant is not able to sell 10 cottons.