maths type question, missing numbers in verbal reasoning

[goldengirl]

Hi,
How do you tackle these sort of questions?
2,5,7,49,70 = 14 = ( / x )
4,5,8,10,16,=,160 =( / x )
The forward slash is instead of a division sign that I can't work out how to find.

I realise that the numbers in the brackets need to = the numbers in the middle ie 14 and 160 but is there a clear method of doing them rather than making random attempts?
Sorry if I sound terribly daft!
Very many thanks

[goldengirl]

Hi-I should have said in my question that the numbers on the left can only be used once.
Thanks lots

[Okanagan]

Do the instructions on the paper make it any clearer whether the question is asking you to
1. use all the numbers, but using only combinations of / x and brackets?
2. use as many of the numbers as you like (each a maximum of once), but not necessarily all, using only combinations of / x and brackets?
or
3. choose 3 of them to make a sum in the form a / b x c?

[Stocky]

Look for anything obvious in the numbers involved, whether its +/-/x etc and the answer required. The last thing you have to do is 'x' and you need to get 14, from the numbers there is only 2 and 7 which go into 14. the first step is divide and the only numbers which are divisible are 70, 49 and 7. 49/7 = 7 (x2) = 14. Also, if the 2 steps involve multiplying or adding, depending on the target number, its unlikely you are going to use the higher numbers, if your target number is small and you have to subtract or divide, then start with bigger numbers.