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
11 of the 329.99 lawn mowers and 19 of the 249.99 lawn mowers
ah, those are systems you want one variable to cancel out. I would time the bottom equation by -1 so x cancels then u solve for y. then u plug all back in to solve for x.
Put this in your calculator or use pictures if you'd like. (3/4) x 12 and you'll get 9