Is my work correct? Please tell me which question is wrong and the answer thx 25 points to correction and answers

What’s the numerical coefficient of 6xy

Two cyclists 84 miles apart start riding toward each other at the same. one cycles 2 times as fast as the other. if they meet 4 hours later, what is the speed (in mi/h) of the faster cyclist?

If a suspect is in possession of 20 grams of cocaine how many ounces does he possess what will the charge be