A) (15/(x+y))*((x+3y)/3x)=
=сокращаем=
=(5(x+3y))/(x(x+y))
f) 4/x^3: ((x^3+2)/x^3)=
при деление дробь переворачивается=
=4/x^3 * (x^3/(x^3+2)=
=4/(x^3+2)
б) x/y : (2y-x)/y=
x/y * (y/(2y-x)= x/(2y-x)
в) (x+3)/(y-4) * ((y-4)/x)=
=(x+3)/x
г) (ab-1)/a) * 3a^2/(ab-1)=
=3a
д) (2b-a)/b): (a-2b)/2b)=
= -(a-2b)/b) * 2b/(a-2b)=
= -2
e) a/(a-b)): ((a+b)(a-b)+b^2)/
/(b(a-b))= a/(a-b)) *
* (b(a-b)/(a^2-b^2+b^2)=
=b/a
ж) (x/(x+y)):((x^2-(x^2-y^2))/(x(x+y))=(x/(x+y)):(x^2-x^2+y^2)/(x(x+y)=
=(x/(x+y) * (x(x+y)/y^2=
=x^2/y^2