Answer:
The white cell count of 8750 is considered healthy.
Step-by-step explanation:
The question calls for any white cell count below 1500 above 7500 to be considered healthy. So, by adding the number 1500 to 7500 we find that the upper limit for being healthy is 9000 white blood cells per cubic millimeter of blood. This all can be represented mathematically with the following:
If:

<em>Then</em>
White blood cell count 'x' is healthy.
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Else if:
<u>or</u> 
<em>Then</em>
White blood cell count 'x' is not healthy.
Now let's test the white cell count of 8750.
<em>Does it fall between 7500 and 9000?</em>

This checks out so the answer is yes: White blood cell count '8750' is healthy.
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