You can put this solution on YOUR website! Log base 0.4 of 24 - log base 4 of 12
applying "change of base" we have:
log(24)/log(0.4) - log(12)/log(4)
-3.4683902388138800504298507119335 - 1.7924812503605780907268694719739
-5.2608714891744581411567201839074
or approximately:
-5.26