If `5^(x)=7^(x+1) `then x is equal to

If 6^(x)=7^(x+1) , then x equals

If (x,3)+(2,5)=(7,8) then x is equal to a)2 b)5 c)7 d)9

If x-1/x=7 , then x^3-1/x^3 is equal to :

If |{:(x,3,6),(3,6,x),(6,x,3):}|=|{:(2,x,7),(x,7,2),(7,2,x):}|=|{:(4,5,x),(5,x,4),(x,4,5):}|=0 then x is equal to