Jon P. answered 07/02/15
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If this is exactly the way it's written...
log5x-1=3
...then it means log(5x)-1=3
To solve...
log (5x) - 1 = 3
Add 1 to both sides:
log (5x) = 4
Exponentiate both sides, with a base of 10 (since log without a base means log10):
10log (5x) = 104
Use the definition of log:
5x = 10000
x = 10000 / 5 = 2000