Find a base 7 three-digit number which has its digits reversed when expressed in base 9.

Question

(You do not need to indicate the base with a subscript for this answer.)

Answer 1

well, using base 10 for now, if the number has base7 digits abc, we need

49a+7b+c = 81c+9b+a

c = 3a/5 - b/40
40c = 24a-b
If c=1, a=2,b=8 Nope
If c=2, a=4,b=16 Nope
If c=3, a=5,b=0

503₇ = 305₉

check:
49*5+3 = 81*3+5
yes

Answer 2

That would be wrong, sorry.

Answer 3

thats actually correct you know?