-3x+5y=-4
5y=3x-4
Y=3/5x-4/5
When it parallel to the line y=3/5x-4/5
It can be y=-3/5x+b
-5=6/5+b
B=-5-6/5=-25/5-6/5=-31/5
Y=-3/5x-31/5
3/5x+y=-31/5
Multiply 5
3x+5y=-31
N x 721 = 72.1
721n = 72.1 (put it in an easier format)
n = 0.1 (divide both sides by 721)
0.074 x n = 74
0.074n = 74 (put it in an easier format)
n = 1000 (divide both sides by 0.074)
12*5*4.25=255 cubic in (total vol.)
.25*.25*.25=1/64 (vol. of small cube)
255/(1/64)=16,320 cubes
Answer:
9 mph = the speed in still water
Step-by-step explanation:
Let r = the speed in still water
Then the speed going down stream is r + 3
and the speed going upstream is r - 3
d = rt or t = d/r
time going downstream is 16/(r + 3) and time going upstream is 16/(r - 3)
The total time was 4 hours, so
Multiply thru the equation by (r + 3)(r - 3)
Then 16(r - 3) + 16(r + 3) = 4(r + 3)(r - 3)
16r - 48 + 16r + 48 = 
- 36
- 36 = 32r
- 32r - 36 = 0
4(r - 9)(r + 1) = 0
r = 9 or -1
But a rate of speed cannot be negative, so x ≠ -1
So, r = 9 mph = the speed in still water
Consider one pyramid
Side length of base = 1.5cm and its height is 1 cm
Slant height of one of the lateral faces = sqrt(1^2 + 0.75^2) = 1.25 cm
Area of one of the triangular faces = 0.5 * 1.5* 1.25 = 0.9375 cm^2
There are 8 of these so the required surface area = 8 * 0.9375
= 7.5 cm^2 Answer
