Log2 16 - log8 64 log7 5 * log25 16 * log4 7 2log5 15 - log5 25 + log5 35 lg 216 / lg6 log4 log3 81

Log2 16 - log8 64=4-2=2

log7 5 * log25 16 * log4 7=    log4 5 *log4 7     = 0,5
                                               2log4 7*log4 5

2log5 15 - log5 25 + log5 35=2log5(15:25*35)=2log5  21

lg 216 / lg6=lg (216-6)=lg 200=2lg 20
log4(log3 81)=log4 4=1