Two friends, Alice and Bob, decide to participate in a charity walkathon. Alice walks at a speed of $4\text{ km/h}$ and Bob walks at a speed of $5\text{ km/h}$. The walkathon lasts for $3$ hours. If Alice donates $10$ for every $km$ she walks and Bob donates $15$ for every $km$ he walks, how much more will Bob donate compared to Alice? Let's think step by step and output the final answer within \boxed{}.
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