Hello jainam shah ,thanks for asking this question on this platform. Firstly in your question you didn't mention about the nature of string that is either they are identical or not .if we assume that they are identical then all three string will produce a tension of value T in upward direction and a gravational forcein downward direction.then T+T+T=100*10

T=333.33 will be the value of tension in any string .thanks