<span>(9^(n-81))/(3^(n-9))=3^(n-153)</span>
(cos20+sin50-cos80)/√(1+cos^2(80))=
=((cos20-cos80)+sin50)/√(1+cos^2(80))=
=(-2sin50*sin30)+sin50)/√(1+cos^2(80))=
=(-sin50+sin50)/√(1+cos^2(80))=0/√(1+cos^2(80))=0
log6 ( -5 - х) = 3
6^3=-5-x
216=-5-x
221=-x
x=-221