12, 54, and 18 so, what he said is true
Step-by-step explanation: he already gave this to you
Answer:
A=12
B=54
C=18
Explanation:
A=first
B=second
C=third
A+B+C=84
B=3C
A=C-6
C-6+3C+C=84
5C-6=84
5C=90
=(18)-6
=12
=3(18)
=54
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