-5х-20=15
-5х=15+20
-5х=35/(-5)
х=-7
2)
-1/х=10
х*(-1/х)=10*х
-1=10х
х=-1/10
х=-0,1
2/3x³ * 9x⁴/4=3x/2
(x+2)*x/3x+6=x/3
(-a³/2b)²=a⁶/4b²
(y-2)(y+2)/3y * 3y²/y(y-2)=y+2
2500:(y-189)=25