Absolute value of any number is always positive because it represent distance and distance will always positive.
To place chimney at least 30 feet , the distance along the width of the roof (x) will be x = 17.5 feet or x = 2.5 feet.
Since, The height of the roof is described by the function f(x)=−4/3|x−10| + 40
Since, minimum height is 30 feet.
So , substitute f(x)=30 in above expression.
30=−4/3|x−10| + 40
4/3|x−10| = 10
|x−10|=30/4
|x−10| = 7.5
Taking positive case,
x−10 = 7.5
x = 17.5 feet
Taking negative case,
x−10 = - 7.5
x = 10 - 7.5
x = 2.5 feet
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4:10 is the time that the class ends, I think that's what you meant?
Answer:

where,
SP=Selling price
CP=Cost price
<h3>
For example:</h3>
Given,
Selling price(SP)= 1000
Cost price(CP)=800
Now,

Hope this helps...
Good luck on your assignment..
Answer: 3
Explanation:
27 = 3^3
42 = 2 x 3 x 7
So the HCF of (27,42) = 3