Question

whydid franklin killed trevor and Michael ​

Answer 1

He has the options to kill or he can kill the boy which was kidnaped by Trevor in car

Answer 2

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After Michael, Franklin and Trevor pull off a major heist on the Union Depository, Franklin is visited by both Steve Haines and Devin Weston. Steve orders Franklin to kill Trevor Philips, due to the latter's uncontrollable temper making him a liability for the FIB.

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