M^2 - n^2 = (m - n)(m + n)
b^2 - n^2 = (b - n)(b + n)
c^2 - (ab)^2 = (c - ab)(c + ab)
5х^3-5ху^2=5х(х^2-у^2)=5х(х-у)(х+у)
P^4-64p^2 = (p^2-8p )(p^2+8p )
...................................
0,18у-7,4=0,05у-5,71
0,18у-0,05у=-5,71+7,4
0,13у=1,69
у=1,69:0,13
у=13