Book I, Problem 18.Find three numbers such that thesum of any pair exceeds the third by a given amount;say the given excesses are 20, 30, and 40. [Hint:Letthe sum of all three numbers be 2x. Add number (3)to both sides of the equation (1)C(2)D(3)C20 toget (3)Dx10. Obtain expressions for (1) and (2)similarly.

Step-by-step explanation:

Let the three numbers be represented by a, b, c. Apparently, we want ...

  a + b = c + 20

  a + c = b + 30

  b + c = a + 40

Adding these three equations gives ...

  2a +2b +2c = a + b + c + 90

Subtracting a+b+c, we have ...

  a + b + c = 90

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Now, we can subtract each original equation from this to find one of the variables:

  (a +b +c) -(a +b) = (90) -(c +20)

  2c = 70

  c = 35

  (a +b +c) -(a +c) = (90) -(b +30)

  2b = 60

  b = 30

  c = 90 -35 -30 = 25

The three numbers are 25, 30, 35.

the answer is: d) o, f, and kr.

atomic radius of bromine (br) is 114 pm.

atomic radius of oxygen (o) is 73 pm.

atomic radius of fluorine (f) is 72 pm.

atomic radius of krypron (kr) is 112 pm.

the atomic radius of a chemical element is a measure of the size of its atom.

the atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

the atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.

where's the diagram?

step-by-step explanation: