7^(3*x-1)=5^(x-1) take the log of both sides
log [7]^(3*x-1) = log [ 5]^(x-1) and we can write this as
(3x - 1)log7 = (x-1)log 5 expand
3x log7 - log 7 = xlog 5 - log 5 rearrange
3x log 7 - x log 5 = log7 - log 5 factor out x on the left side
x [ 3 log 7 - log 5] = log 7 - log 5 divide both sides by [ 3 log 7 - log 5]
x = [ log7 - log 5] / [ 3log 7 - log 5] = about .0796
