MATH PUZZLE: Can you replace...

Two sisters, one blonde and one brunette, inherit the family ranch. Unfortunately, after just a few years, they are in financial trouble. In order to keep the bank from repossessing the ranch, they need to purchase a bull from the stockyard in a far town so that they can breed their own stock.

They only have $600 left. Upon leaving, the brunette tells her sister, 'When I get there, if I decide to buy the bull, I'll contact you to drive out after me and haul it home.'

The brunette arrives at the stockyard, inspects the bull, and decides she wants to buy it. The man tells her that he will sell it for $599, no less. After paying him, she drives to the nearest town to send her sister a telegram to tell her the news. She walks into the telegraph office and says, 'I want to send a telegram to my sister telling her that I've bought a bull for our ranch. I need her to hitch the trailer to our pickup truck and drive out here so we can haul it home.'

The telegraph operator explains that he'll be glad to help her, then adds, 'It's just 99 cents a word.' Well, after paying for the bull, the brunette only has $1 left. She realizes that she'll only be able to send her sister one word.

After a few minutes of thinking, she nods and says, 'I want you to send her the word 'comfortable.'

The operator shakes his head. 'How is she ever going to know that you want her to hitch the trailer to your pickup truck and drive out here to haul that bull back to your ranch if you send her just the word 'comfortable?'

The brunette explains, 'My sister's blonde. The word's big. She'll read it very slowly ... com-for-da-bull.'