Betty and Wilma both sell cookies to earn money for a trip. Betty charges $2 per cookie and Wilma charges $1.50 per cookie. If Betty has to pay $1.50 for her secret ingredient, how many cookies, x, must they each sell before they have the same amount of money?

Answer 1

Let's assume Betty sells x cookies.
The amount of money Betty earns from selling x cookies is 2 * x = <<2*x=2x>>2x dollars.
Betty has to pay $1.50 for her secret ingredient, so the amount of money Betty is left with is 2x - $1.50.
Wilma charges $1.50 per cookie, so to earn the same amount of money as Betty, she needs to sell 2x - $1.50 / $1.50 = (2x - $1.50) / $1.50 = 1.333...x cookies.
Since we can't sell a fraction of a cookie, they must each sell x = 2 * x - $1.50 / $1.50 = 4x - $1.50 / $1.50 = 3.5x - $1.50 / $1.50 = 3.5 cookies to have the same amount of money. Answer: \boxed{3}.