Answer: the speed of the boat on the lake is 9 mph
Step-by-step explanation:
Let x represent the speed of the boat on the lake or in still water.
The speed of the current in a river is 6 mph. This means that if the boat goes upstream against the speed of the current, its total speed would be (x - 6)mph. If the boat goes downstream against the speed of the current, its total speed would be (x + 6)mph.
Time = distance/ speed
Every day, his route takes him 22.5 miles each way against the current and back to his dock, and he needs to make this trip in a total of 9 hours. This means that the time taken to travel upstream is
22.5/(x - 6). The time taken to travel downstream is
22.5/(x + 6)
Since the total time is 9 hours, it means that
22.5/(x - 6) = 22.5/(x + 6)
Cross multiplying, it becomes
22.5(x + 6) + 22.5(x - 6) = 9
Multiplying through by (x + 6)(x - 6), it becomes
22.5(x - 6) + 22.5(x + 6) = 9[(x + 6)(x - 6)]
22.5x - 135 + 22.5x + 135 = 9(x² - 6x + 6x - 36)
22.5x + 22.5x = 9x² - 324
9x² - 45x - 324 = 0
Dividing through by 9, it becomes
x² - 5x - 36 = 0
x² + 4x - 9x - 36 = 0
x(x + 4) - 9(x + 4) = 0
x - 9 = 0 or x + 4 = 0
x = 9 or x = - 4
Since the speed cannot be negative, then x = 9
3,952 x 20=79,140
P.S. Not be rude but do you have a caculator?
-Nana
Answer:
13%
Step-by-step explanation:
the total amount:16,000,Amount of people:13,920
13,920/16,000=87% of people who showed up
100%-87%=13%
<span>
<span>
</span><span><span>
<span> Selling Price </span>
<span> Cost </span> <span> Profit </span>
<span> Mark up </span>
</span>
<span>
<span>
75.99 </span>
<span> 61.00 </span>
<span> 14.99 </span>
<span> 0.25
</span></span><span><span> 29.95 </span>
<span> 23.75 </span>
<span> 6.20 </span>
<span> 0.26</span></span><span><span>
19.25 </span>
<span> 15.00 </span>
<span> 4.25 </span>
<span> 0.28</span></span><span><span>
1.50 </span><span> 1.19 </span>
<span> 0.31 </span>
<span> 0.26</span></span><span><span>
54.99 </span>
<span> 44.55 </span>
<span> 10.44 </span>
<span> 0.23</span></span><span><span>
12.95 </span>
<span> 10.80 </span>
<span> 2.15 </span>
<span> 0.20
Profit = Selling price - Cost
Mark up = Profit / cost </span></span></span></span>
Convert everything to terms of sine and cosine:
The factors of 
cancel to give
