ElectricPavlov

....this was answered in your last question too......

2 x 4 window with 7 ft^2 border

border   is   2 sides x 4 tall x w  on the long sides  

  and on the top/bottom  will be  2 sides x (2 ft + 2w) * w

     added together = 7    (w will be in feet)

2 x 4 x w + 2 x (2 + 2w)w = 7

8w  + 2 (2w+2w^2) =7

8w + 4w + 4w^2 = 7

4w^2 + 12w - 7 = 0     Use Quadratic FOrmula to find w = .5    or (-3.5) <-----throw out

w = .5 ft   = 6 inches  width of border

Yah, it is wrong....I fixed it.....

Your friend has a head start   3 m/hr  5/60 = 1/4 mile

at the difference in your speeds   4 - 3 = 1 mph

    it will take   1/4 mile / 1 m/hr = 1/4 hr    (15 minutes ) to catch up to her...    PLUS the 5 minutes she was walking before you started = 20 minutes

Information is missing, but your friend will have travelled (at the point you in time you start)

    rate x time = distance

    m/hr x minutes/60 = distance in miles

Parallel, so slope is the same     -3/5

point slope form

(y-(-1)) = -3/5 (x-(-5)

y+1 = -3/5 (x+5)  

Re-arranging point slope form

y+1 = -3/5 x  -3

y = -3/5 x -4 

12g is distance on g liters

12 (5.5) = distance on 5 1/2 liters

   = 66 km

2*6+2*x=48

12 + 2x = 48     subtract 12 from each side of the equation

2x = 36             divide both sides by 2

x = 18

yf = yo e^-kt

18 .8 = 24e^{(-k 18)}

^{k = .0135665}

^{1/2 of 24 is 12 grams remaining at t = 1/2 life}

12= 24e^{-(.051287 t)}

Solve for t = 51.09 days

f(8) = -2

f(64) = -4

rate of change      (-4 - -2)/( 64-8)  =    -2 / (56) = -1/28