Question: This is an IQ question.

"Catherine is now twice as old as Jason but 6 years ago she was 5 times as old as he was. How old is Catherine now?"

How to solve such questions? I think their combined age should be given but its not.

Answer: 
It can be helpful to organize the information into a 'now-and-then' chart. Let Jason's age now be $J$.

$$\begin{array} {c|c|c} &\mbox{Jason's age}&\mbox{Catherine's age} \\ \hline
\mbox{Now} &J&2J\\ \mbox{6 years ago} &J-6& 2J-6 \end{array}$$

Then $2J-6=5(J-6)$, which you can easily solve.
**hint**: Let $C,J$ be Kathy's and Jason's ages as of now. Thus: $C = 2J , C-6 = 5(J-6)$. Can you finish it off?