The Billionaires' Love Bet

This is the first book of The Hot Billionaires series. Though it is a series, each book can be read as a stand-alone.
"Shall we make a bet? Whoever manages to get the girl to become our girlfriend can win the favorite thing they want." Robert said.
"You're mad! Why should we bet on something like that?" Alex shook his head, then folded his arms in front of his chest.
"Just to be a girlfriend? It's too low a target, bro. What if until having sex?" Arya challenged the others. His eyes were shining.
Robert laughed out loud. "No problem! I'm not afraid. But if it comes to sex, the prize must be bigger."
"Fine! I'll bet my Jaguar. You should bet on your new apartment, Bert." Afterward, Arya looked at Alex, still leaning on the sofa with his arms crossed over his chest. "Are you in?" Then Arya's gaze turned to Jeremy. "Jem?"
"Of course!" Jeremy grinned. "I bet my gold deposit. It's worth 2 billion."
Four billionaires (Arya, Robert, Alexander, and Jeremy) spot Amira, a beautiful and sexy lady, but an unapproachable one. They see Amira as a new challenge and start to make a bet to make her their girlfriend. Who will win the bet in the end?