Alan

Presumably you are looking for the difference between these two numbers:

range = 0.005 - (-1.205) 

range = 0.005 + 1.205 

range = 1.21

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6% means 6 parts in 100, so to find 6% of 9000 just multiply 9000 by 6 and divide the result by 100.

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The longer leg (by which I presume you don't mean the hypotenuse!) is √3 times bigger than the shorter leg.

Hence shorter leg = 18/√3 ≈ 10.39

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Let P be the original price.  

30% of P is 0.3*P, so $15 = P - 0.3P  or $15 = 0.7P

Divide both sides by 0.7 to get P:  P = $15/0.7 = $21.43  or $21 43cents

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A + B + C = 75

A - 28 +19 = 75/3

A - 9 = 25

A = 34

B  - 24 + 28 = 75/3

B + 4 = 25

B = 21

C - 19 + 24 = 75/3

C + 5 = 25

C = 20

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What does the "u" stand for?

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16*23 = 368

16+23 = 39

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Press the 2nd button and you will see atan appear.  This is the same as tan^-1

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Find the prime factors of each:

$${factor}{\left({\mathtt{2\,814\,749\,767\,109}}\right)} = {\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{65\,111}}{\mathtt{\,\times\,}}{\mathtt{6\,175\,717}}$$

$${factor}{\left({\mathtt{59\,482\,661\,568\,307}}\right)} = {\mathtt{7\,577\,329}}{\mathtt{\,\times\,}}{\mathtt{7\,850\,083}}$$

No factor in common, therefore they are relatively prime.

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The following graph should help (remembering that the area of a triangle is half base times height):

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