log3x - log13 = 2
This is to base 10, because the base was not specified.
log A - log B = log(A/B) law of logarithm
log(3x/13) = 2
By law of logarithm, conversion from logarithm to indices
(3x/13) = 10²
3x/13 = 100
3x = 100*13
x = 1300/3
x = 1300/3 = 433 1/3