Answer:
84
Step-by-step explanation:
56/2 = 28
28 x 3 = 84
To check work: 84/3 =28
Answer: 54 mph
Step-by-step explanation:
d-the distance
s+9 - the speed to the conference
d=6*(s+9)
s- is the speed on the way back home
d=7*s
so 6*(s+9)=7*s
6s+54=7s
-6s -6s
54= 7s-6s
s=54 mph