<span>6 km × 1 hour/(b-4 km) = 12 km × (1 hour/(b+4 km)
6/(b-4) hours = 12/(b+4) hours
6(b+4) = 12(b-4)
6b + 24 = 12b - 48
72 = 6b
b = 12
The boat's speed in still water is 12 km/hour.</span>
The answer a are
1 C
2 A
3 whatever letter has the the answer 5x10^10
Answer:
7500 ft
Step-by-step explanation:
5 x 10 x 10 x 15
(50) x 10 x 15
(500) x 15
(7500)
check the pictured below.
now, notice that APB is just a flat-line and therefore those two angles there add up to 180°.
also notice that since ∡ACB is 90°, then those two angles add up to that much.
![\bf \stackrel{\measuredangle ACP}{(3x+2y)}+\stackrel{\measuredangle BCP}{(3x+4y)}=90\implies 6x+6y=90\implies \stackrel{\textit{common factor}}{6(x+y)}=90 \\\\\\ x+y=\cfrac{90}{6}\implies x+y=15\implies \boxed{x=15-y} \\\\[-0.35em] ~\dotfill](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7B%5Cmeasuredangle%20ACP%7D%7B%283x%2B2y%29%7D%2B%5Cstackrel%7B%5Cmeasuredangle%20BCP%7D%7B%283x%2B4y%29%7D%3D90%5Cimplies%206x%2B6y%3D90%5Cimplies%20%5Cstackrel%7B%5Ctextit%7Bcommon%20factor%7D%7D%7B6%28x%2By%29%7D%3D90%0A%5C%5C%5C%5C%5C%5C%0Ax%2By%3D%5Ccfrac%7B90%7D%7B6%7D%5Cimplies%20x%2By%3D15%5Cimplies%20%5Cboxed%7Bx%3D15-y%7D%0A%5C%5C%5C%5C%5B-0.35em%5D%0A~%5Cdotfill)
![\bf \stackrel{\measuredangle APC}{(7x+3)}+\stackrel{\measuredangle BPC}{(16y)}=180\implies 7x+16y=177\implies 7\left( \boxed{15-y} \right)+16y=177 \\\\\\ 105-7y+16y=177\implies 9y=72\implies y=\cfrac{72}{9}\implies \blacktriangleright y=8 \blacktriangleleft \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \measuredangle BPC=16(8)\implies \measuredangle BPC=128](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7B%5Cmeasuredangle%20APC%7D%7B%287x%2B3%29%7D%2B%5Cstackrel%7B%5Cmeasuredangle%20BPC%7D%7B%2816y%29%7D%3D180%5Cimplies%207x%2B16y%3D177%5Cimplies%207%5Cleft%28%20%5Cboxed%7B15-y%7D%20%5Cright%29%2B16y%3D177%0A%5C%5C%5C%5C%5C%5C%0A105-7y%2B16y%3D177%5Cimplies%209y%3D72%5Cimplies%20y%3D%5Ccfrac%7B72%7D%7B9%7D%5Cimplies%20%5Cblacktriangleright%20y%3D8%20%5Cblacktriangleleft%0A%5C%5C%5C%5C%5B-0.35em%5D%0A%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%0A%5Cmeasuredangle%20BPC%3D16%288%29%5Cimplies%20%5Cmeasuredangle%20BPC%3D128)