Would this work? (20 characters)?

I don't think thats a good idea. Going in half is never a good idea. What if the horse gets sick? Will you still split the costs? And you will never make your money back. By the time you figure up the cost of feed, vet, shoes, etc for the time you have him you will never make money off him. This horse might seem good now but its prolly just a new thing and you will not like him so much in a few weeks. Like a new toy a 2 year old gets and loves for a few weeks then its not so great. Not comparing a horse to a toy, but you prolly get my point. If in another month you still love this horse and want to go in half for him, get absolutly everything is writing! Figure out exactly who will pay for what and how to divide the cost up. It wouldn't take much for the two of you to have a fall out over argueing over money. She might be your friend and trainer but still have a paper signed about how you two will pay for the horse.