Answer:
83.5
Step-by-step explanation:

See this solution/explanation (answer is '7 meters'):
1. According to the condition 'y' means the height, and 'x' - the length from the start of the lift hill.
2. The phrase 'height of 343 meters' means y=343.
3. From the another side y=x³. If to substitute 343 instead of 'y': 343=x³, - it is possible to find the value of 'x'.
x=<u>7 [m]</u> - how far from the start of the lift hill...
Again, nice problem. These are not super easy. You need to imagine the triangles in the figure and relate sides.
For instance: ADC, its hypotenuse is 15
For ABC, it is 20,
so 20/15 is the ratio between both triangles. Now let's choose the side with 'x'
x is one side of ADC, the corresponding side in ABC is 15 (the second longest sides). You need to rotate the triangles, etc ... That's the tricky part :)
So:
20/15 =15/x ----> x = 15*15/20 = 225/20 = 45/4
Which is C
Not sure whether it's too late to help you though!!!!
Also notice that it's kind of a product rule:
x * 20 = 15 * 15
I am sure the book explains a short way of getting to this equation, like sides opposite, blah blah, but what i told you is the reason. You asked for understanding it! Best luck!
Articles of clothing that the store received last Thursday is 84
<u>Solution:</u>
Given that
A clothing donation store received numerous articles of clothing on Thursday of last week.
The number of articles of clothing that the store received last Thursday is represented by the following expression:
4 (3x − 1) − 2 (6 + 2x)
Need to calculate articles of clothing that the store received last Thursday when x = 12.5
As on Thursday x = 12.5, need to substitute x = 12.5 in above equation to get number of articles received on Thursday.
On substituting x = 12.5, we get
4 ( (3 x 12.5 ) – 1 ) – 2 ( 6 + ( 2 x 12.5 ) )
=> 4 (37.5 – 1) – 2 (6 + 25)
=> 146 – 62 = 84
On substituting x = 12.5 , we are getting value of expression as 84.
Hence articles of clothing that the store received last Thursday is 84