This was the answer I came up with - 3.5
Givens
<em><u>Slower car</u></em>
r = r
t = 12 hours
d = ?
<em><u>Faster car</u></em>
r = r + 20
t = 8 hours
d = ?
It doesn't matter what the exact distance is. You just have to know that the 2 distances are equal ie going to the mountains from his home is the same distance as going from the mountains to his home.
d = r * t
r * 12 hours = (r + 20)* 8 hours. Remove the brackets on the right
r*12 = 8r + 20*8
r*12 = 8*r + 160
r*12 - 8r = 8r - 8r + 160
4r = 160
r = 40 miles / hour
=================
Slower Ride determines the distance.
d = r*t
d = 40 * 12
d = 480
Check
Use the faster rate (r + 20) = 40 + 20 = 60 mph
60 * 8 = 480. Both distances work out to be the same.
As we can see on the picture we have a rectangle and half of circle.
The areas for half circle and rectangle are:
The area of the figure is the sum of the area of half circle and rectangle. Also the height of a rectangle (6ft) is a diameter of a half circle therefore the radius of half circle is 6ft ÷ 2 = 3ft.
Now we calculate the areas.
The area of the figure is approximately 74ft squared.
Hope this helps.
r3t40
Dup= 72 miles
<span>ddown= 120 miles </span>
<span>v= riverspeed </span>
<span>rup= 32mph - v </span>
<span>rdown= 32mph + v </span>
<span>t both ways= t </span>
<span>d=r*t </span>
<span>d/r=t </span>
<span>t=ddown/rdown </span>
<span>t=dup/rup </span>
<span>dup/rup = ddown/rdown </span>
<span>(72)/(32-v)=(120)/(32+v) </span>
<span>3840-120v=2304+72v </span>
<span>1536=192v </span>
<span>v=8</span>
Easy, take:
p-4=-9+p
Isolate the variable, this is what you are trying to find (p)
p-4=-9+p
-p -p
-4=-9.
There is no variable, which means, there is NO SOLUTION!
You can put no solution, or ∅, as an answer.
