He increases the time he can run by 8*.75=<<8*.75=6>>6 hours

So he can now run 8+6=<<8+6=14>>14 hours

His speed is now 8+4=<<8+4=12>>12 mph

So he can run 14*12=<<14*12=168>>168 miles

# Answer

168
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
John trains for ultramarathons.  He starts only able to run 8 hours straight but eventually increases that by 75%.  He also increases his speed of 8 mph by 4 mph.  How far can he run now?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
168
John trains for ultramarathons.  He starts only able to run 8 hours straight but eventually increases that by 75%.  He also increases his speed of 8 mph by 4 mph.  How far can he run now?
train