1)log(3)90×0,3=log(3)27=log(3)3^3=3
2)2log(2) 12+log(2) 20-log(2)15-log(2)3=log(2) 144×20
=log(2)2880/15=log(2) 192/3=log(2) 64=log(2)2^6=6
3)log(3)54-log(2)v2-log(3)2=log(3)54-log(2)2^-1-log(3) 2=(log(3) 54/2)+1=log(3)3^3+1=3+1=4
просто используй свойства