You can
put this solution on YOUR website!Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r
Let r=rate or speed of boat in still water
Upstream, we subtract speed of current; downstream we add
Time to travel downstream=36/(r+3)
Time to travel upstream=36/(r-3)
Now we are told that the time upstream is one hour longer than the time downstream, so:
(36/(r+3))+1=36/(r-3) multiply each side by (r+3)(r-3)
36(r-3)+(r+3)(r-3)=36(r+3) get rid of parens
36r-108+r^2-9=36r+108 subtract 36r and also 108 to each side:
36r-108-108+r^2-9-36r=36r-36r+108-108 collect like terms
r^2-216-9=0
r^2-225=0 add 225 to each side
r^2=225 take square root of each side
r=+ or -15 mph negelect the negetive value for r; speeds are positive
r=15 mph------------------speed of boat in still water
CK
(36/18)+1=36/12
2+1=3
3=3
Hope this helps---ptaylor
