Answer:
The rate of the current is 2 miles per hour.
Step-by-step explanation:
Let us assume that the rate of the river is v miles per hour.
The speed of the boat is 12 miles per hour.
Let us assume also that the boat can go 21 miles in t hours in the downstream and 15 miles upstream at the same time i.e. t hours.
So, from the condition given we can write that
......... (1), and
......... (2)
Now, adding those two equations we get
⇒
hours
Now, from equation (1), we get,
⇒ v = 2 miles per hour
Therefore, the rate of the current is 2 miles per hour. (Answer)
<span>2x^2 +3x -4 + 8 - 3x -5x^2 +2
answer is
</span>-3x^2 +6
hope that helps