Hint: You can either fix the distance rowed and see what numbers work, or you can fix the number of hours.
Answer: 12 miles.
In the morning, rowing at 2 miles per hour, they rowed for 6 hours. In the afternoon, rowing at 4 miles per hour, they rowed for 3 hours. QED.
There are a number of ways of working this out, and here are two of them:
If we assume the distance the rowed upstream to be D miles, we know the morning took (D ÷ 2) hours, and the afternoon took (D ÷ 4) hours, with a difference of 3 hours. So:
D D 3
- - - =
Multiplying throughout by 2, and then 4, gives:
4D - 2D = 24
2D = 24
D = 12 miles.
They rowed 12 miles upstream. QED.
If we assume they rowed for H hours upstream, we know they travelled H x 2 miles in the morning. In the afternoon they rowed for (H - 3) hours, and travelled (H - 3) x 4 miles. We know these distances are the same, so:
2H = (H - 3) x 4
2H = 4H - 12
12 = 2H
H = 6 hours.
They rowed for 6 hours upstream at 2 miles per hour, which is a total of 12 miles. QED.
Hint: 2 arrows point to the right, and the others point to the left.
Using the BrainTracker grid below, how many words can you find? Each word must contain the central H and no letter can be used twice, however, the letters do not have to be connected. Proper nouns are not allowed, however, plurals are. Can you find the nine letter word?