Truth vs Lie possibility A, B and C tell the truth independently with probabilities $1/3, 1/4, 1/5$ respectively. C makes a statement and B says that C has lied , whereas A says that C has told the truth. Find the probability that C made a true statement.
I did
$$(1*1*3/3*4*5)/[(1*1*3/3*4*5)+(4*2*1/5*4*3)]$$
Is this correct?

Your expression is a bit difficult to read, but yes, that is correct. What you've done I assume is work out the probability $p$ of A and C telling the truth and B lying, and the probability $q$ of A and C lying and B telling the truth. We know one of these two things has happened, and so the probability that it is the first one is $\frac{p}{p+q}$. You can cancel the $3\times 4\times 5$ in your answer, so this becomes
$$\frac{1\times 1\times 3}{1\times 1\times 3+4\times 2\times 1}=\frac3{11}.$$
