3^-8*5^-4/5^-2*3^-10=3^(-8+10)*5^(-4+2)=3²/5²=9/25
2^7/5*2^1/2*2^0.3/2^4/5/2^4/5*2^0.4=2^(7/5+1/2+0.3-4/5-0.4)=
=2^(11/10-0.1)=1
В)
-45f^3x*(x-8)*(x+20)
(-45f^3x^2+360f^3x)*(x+20)
-45f^3x^3-540f^3x^2+7200f^3x
ab^2=5/2. 7ab^2=3,5*2ab^2=3,5*5=17,5. -4a^2b^4= -(2ab^2)^2= -(5)^2= -25. в последнем не уверен. скорее всего нет.