text: how 2 do...............? 1) log 90 + log(13/45) - log (8/13) + 4 log5 log 90 + log(13/45) - log (8/13) + 4 log5 = log (90 (13/45) )- log (8/13) +  log5^4 = log (26 )- log (8/13) +  log5^4 = log (26 /(8/13) ) +  log5^4 = log ( 26(13)/8) + log 5^4 = log (13(13) /4)  + log 5^4 = log ( 13^2 5^4  /4) ~