Question 166524
Distance(d) equals Rate(r) times Time(t) or d=rt;  r=d/t and t=d/r

Let r=speed of the current
Time to travel upstream=2.3/(3-r)  (Note: Upstream we have to subtract the speed of the current; downstream, we add)
Time to travel downstream=2.4/(3+r)

Now we are told that the above two times are equal, so:
2.3/(3-r)=2.4/(3+r)  multiply each side by (3-r)(3+r) (or cross multiply)
2.3(3+r)=2.4(3-r) get rid of parens (distributive law)
6.9+2.3r=7.2-2.4r subtract 6.9 from and add 2.4r to each side
6.9-6.9+2.3r+2.4r=7.2-6.9-2.4r+2.4r  collect like terms

4.7r=0.3  divide each side by 4.7
r=0.0638 mph -----------------------speed of the current

CK
2.3/(3-0.0638)=2.4/(3+0.0638)
0.783=0.783

Hope this helps---ptaylor