Answer:
4.1 billion
Step-by-step explanation:
1 ft = 30.48 cm
1 in = 2.54 cm
The volume of rain that fell on the roof is given by ...
V = LWH
V = (175 ft × 30.48 cm/ft)(45 ft × 30.48 cm/ft)(11 in × 2.54 cm/in)
= 175×45×11×30.48²×2.54 cm³ = 204,412,236.336 cm³
At 20 drops per cm³, this will be ...
20×204,412,236.336 ≈ 4,088,244,727 . . . . raindrops
About 4.1 billion raindrops fell on your roof.
All will apply except for (A, C, and E) because those lengths are less than 4/6. So (B, D and F) are the correct answers.
A.
(64x<span>² + 96x + 36) / (16x + 12)
= 4(16x</span><span>² + 24x + 9) / 4(4x + 3)
= 4*(4x + 3)(4x + 3) / 4(4x + 3)
= 4x + 3
b.
1.79 x 10^5 = 1.79 * 100,000 = 179,000
c.
(5.9736 x 10^24) + (4.8685 x 10^24)
= (5.9736 + 4.8685) x 10^24
= 10.8421 x 10^24
= 1.08421 x 10^25</span>
So... hmm bear in mind, when the boat goes upstream, it goes against the stream, so, if the boat has speed rate of say "b", and the stream has a rate of "r", then the speed going up is b - r, the boat's rate minus the streams, because the stream is subtracting speed as it goes up
going downstream is a bit different, the stream speed is "added" to boat's
so the boat is really going faster, is going b + r
notice, the distance is the same, upstream as well as downstream
thus
![\bf \begin{cases} b=\textit{rate of the boat}\\ r=\textit{rate of the river} \end{cases}\qquad thus \\\\\\ \begin{array}{lccclll} &distance&rate&time(hrs)\\ &----&----&----\\ upstream&48&b-r&4\\ downstream&48&b+4&3 \end{array} \\\\\\ \begin{cases} 48=(b-r)(4)\to 48=4b-4r\\\\ \frac{48-4b}{-4}=r\\ --------------\\ 48=(b+r)(3)\\ -----------------------------\\\\ thus\\\\ 48=\left[ b+\left(\boxed{\frac{48-4b}{-4}}\right) \right] (3) \end{cases}](https://tex.z-dn.net/?f=%5Cbf%20%5Cbegin%7Bcases%7D%0Ab%3D%5Ctextit%7Brate%20of%20the%20boat%7D%5C%5C%0Ar%3D%5Ctextit%7Brate%20of%20the%20river%7D%0A%5Cend%7Bcases%7D%5Cqquad%20thus%0A%5C%5C%5C%5C%5C%5C%0A%0A%5Cbegin%7Barray%7D%7Blccclll%7D%0A%26distance%26rate%26time%28hrs%29%5C%5C%0A%26----%26----%26----%5C%5C%0Aupstream%2648%26b-r%264%5C%5C%0Adownstream%2648%26b%2B4%263%0A%5Cend%7Barray%7D%0A%5C%5C%5C%5C%5C%5C%0A%0A%5Cbegin%7Bcases%7D%0A48%3D%28b-r%29%284%29%5Cto%2048%3D4b-4r%5C%5C%5C%5C%0A%5Cfrac%7B48-4b%7D%7B-4%7D%3Dr%5C%5C%0A--------------%5C%5C%0A48%3D%28b%2Br%29%283%29%5C%5C%0A-----------------------------%5C%5C%5C%5C%0Athus%5C%5C%5C%5C%0A48%3D%5Cleft%5B%20b%2B%5Cleft%28%5Cboxed%7B%5Cfrac%7B48-4b%7D%7B-4%7D%7D%5Cright%29%20%5Cright%5D%20%283%29%0A%5Cend%7Bcases%7D)
solve for "r", to see what the stream's rate is
what about the boat's? well, just plug the value for "r" on either equation and solve for "b"
So say for example u have -7 - (-5), think of subtracting integers as adding the opposite, so ur adding the opposite of -5, the opposite of -5 is 5, so ur adding -7 and 5= -2
another one: -15 - (-18)
again, adding the opposite. -15 plus positive 18= 3