Can I please get some help with 2 word problems? I'll have them posted in the comments.

Question

anonymous · Answer

Sure go ahead.

anonymous · Answer

Chris and his brother leave the same point and run in opposite directions on a straight road. After running  for 3 hrs they are 18 miles apart. If Chris runs an average of 1 mph faster than his brother, what is Chris's average speed?

anonymous · Answer

Traveling at full speed on a river, it takes 2 hrs for a motorboat to travel 8 miles downstream and 4 miles back upstream. If the current's speed is 2 mph, what is the maximum speed of the boat in still water?

phi · Answer

for the first problem, after 3 hrs they are 18 miles apart.  That means they are separating at 6 mph , right?  the speed of chris + speed of brother = 6
c+(c-1)=6  (chris runs faster than his bro)
2c-1=6
2c=7
c= 3.5
his bro 2.5 mph (not much of a run)