Hi Kristy.
Let R be Romo's speed relative to the water.
Let T_{a } be the time he spends paddling away from his starting point.
Let T_{b } be the time he spends paddling back towards his starting point.
It doesn't matter to the total time whether he paddles before lunch or after lunch (assuming he doesn't get a cramp), so let's just assume (mathematicians say "without loss of generalization") he travels against the current first.
Since distance equals time x speed, we can write:
28 = T_{a }(R3)
28 = T_{b }(R+3)
and the total time is:
T_{a } + T_{b } + .5 = 6
Now you have three equations with three unknowns. Solve the first two for T_{a } and T_{b }, add them together and substitute into the third equation. Solve for R, your answer.
Hope this helps,
Stephen La Rocque.
