Respuesta :
Gliberia 's one time investment =145$
Now she pays 3$cleaning products each time she washes a car.Her profit each time would then be 12$, but she only starts making profit when her cost of advertising is earned /compensated.
Therefore she will not make any profit till the 145/12=12th(approx) time she washes a car.From the 13th time she washes a car ,she stars earning a profit of 12$ each time!
Hope you find it useful :)
From the 13th time she washes a car ,she stars earning a profit of 12$ each time