Answer:
b = 7
Explanation:
You can start with either inequality, then add the required amount to make it look like the other one.
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Starting with x > -21
x > -21
x + 7 > -14 . . . . . add 7 to both sides
b = 7 . . . . . . . . . compare to the form x + b > -14
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Starting with x + b > -14
x + b > -14
x + b -7 > -21 . . . add -7 to both sides
b -7 = 0 . . . . . . compare to the form x > -21. 0 is added to x.
b = 7 . . . . . . . . add 7 to both sides