У+2/5=13
у=13-2/5
у=12 3/5
х-1/6=7/9
х=7/9+1/6
х=14/18+3/18
х=17/18
у-3/8=5/32
у=5/32+3/8
у=5/32+12/32=17/32
у+2/5=1/2
у=1/2-2/5
у=5/10-4/10=1/10
4867x27=131409
5708x19=108452
:)
=20*(lg(75*25)+lg(10*10))-60=20*(lg(5^4)+lg3+lg(10^2))-60=
80lg5-20lg3+40-60 = 80lg5-20lg3-20