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To answer this question, you must first isolate the given variable, a. Treat the < sign as an equal sign, in that what you do to one side, you do to the other.
Do the opposite of PEMDAS. PEMDAS is the order of operations, and stands for:
Parenthesis
Exponents (& roots)
Multiplications
Divisions
Additions
Subtractions
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First, subtract 8a and add 6 to both side inequality.
a (-8a) - 6 (+6) < 15 (+6) + 8a (-8a)
a - 8a < 15 + 6
-7a < 21
Next, isolate the variable, a, by dividing -7 from both sides of the equation. Note that, when dividing or multiplying by a negative number, you must flip the sign:
(-7a)/-7 < (21)/-7
a < 21/-7
a > -3
a > -3 is your answer.
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