Using absolute value, it is found that:
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[tex]|x| = x, x \geq 0[/tex]
[tex]|x| = -x, x < 0[/tex]
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Item a:
The temperature should be set to 76ºF with an allowance of 4ºF, thus, the absolute value of the difference between the temperature T and 76 should be 4, that is:
[tex]|T - 76| = 4[/tex]
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Item b:
There are two solutions:
[tex]T - 76 = 4[/tex]
[tex]T = 80[/tex]
Or also:
[tex]T - 76 = -4[/tex]
[tex]T = 72[/tex]
A similar problem is given at https://brainly.com/question/22532602