



 
Koteawarao, When you are working in base 7 the only "digits" allowed are 0, 1, 2, 3, 4, 5 and 6. In your answer you have the digit 8 so the answer given can't be correct. The symbol 8 has no meaning in base 7. To solve your problem you want digits a, b and c so that
where a, b and c are either 0, 1, 2, ... ,6. Using the definition of numbers expressed in different bases this can be written
On simplification this becomes
Hence 4 divided b and since b = 0, 1, ..., 6 either b = 0 or b = 4. If b = 0 then 6a = 10c. You know that a and c are between 0 and 6 so what values of a and c make 6a = 10c? Check the values you obtained for a, b and c solve the problem. If b = 4 then 6a  10c = 1. Check all possible values of a and c. Do you find a solution. I found two choices for a, b and c that solve the problem. Harley  


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