00:01
Okay, so now let's look at this problem number 27.
00:03
Here i made the table to summarize all the, summarize all the key information.
00:11
So we know that this trip is 72 kilometers.
00:18
Okay, so here is also 72.
00:29
Okay.
00:31
The return journey is same as the start journey.
00:36
So let's assume that the rate, the speed jesus travels in steel water is let's see vj okay so let's see with current we know the speed of the current is two kilometers per hour so here we have vg plus two and against current is vj minus two so the time with the current we have 72 over vg plus two and against current we have 72 or over vg minus 2.
01:31
We also have a key information that is, it takes our nine hours last time for the trip to the camp area, you know, then the return trip.
01:48
So we know that we can list the equation, which is 72 over vg plus 2 plus 9 equals to 72 vj minus 2.
02:23
So now let's solve for this equation.
02:26
Let's solve for vj.
02:35
First step, let's multiply vj plus 2 and times vj minus 2 to the both side of the equation.
02:43
So we have 72 times vg minus 2 plus 9 times vg minus 2.
02:57
Vj minus times vg plus 2 equals to 172 22 times vg plus 2...