zanaik89 wrote:
Bunuel wrote:
12. If 6a=3b=7c, what is the value of a+b+c?
Given:\(6a=3b=7c\) --> least common multiple of 6, 3, and 7 is 42 hence we ca write:\(6a=3b=7c=42x\) , for some number\(x\) -->\(a=7x\) ,\(b=14x\) and\(c=6x\) .
(1) ac=6b -->\(7x*6x=6*14x\) -->\(x^2=2x\) -->\(x=0\) or\(x=2\) . Not sufficient.
(2) 5b=8a+4c -->\(5*14x=8*7x+4*14x\) -->\(70x=80x\) -->\(10x=0\) -->\(x=0\) -->\(a=b=c=0\) -->\(a+b+c=0\) . Sufficient.
Answer: B.
Given:\(6a=3b=7c\) --> least common multiple of 6, 3, and 7 is 42 hence we ca write:\(6a=3b=7c=42x\) , for some number\(x\) -->\(a=7x\) ,\(b=14x\) and\(c=6x\) .
(1) ac=6b -->\(7x*6x=6*14x\) -->\(x^2=2x\) -->\(x=0\) or\(x=2\) . Not sufficient.
(2) 5b=8a+4c -->\(5*14x=8*7x+4*14x\) -->\(70x=80x\) -->\(10x=0\) -->\(x=0\) -->\(a=b=c=0\) -->\(a+b+c=0\) . Sufficient.
Answer: B.
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