Если именно в процентах,то 21.875,либо же 7 тридцать вторых
Надо найти общиз знаменатель, в данном случаи это 27. 1/27+15/27+9/27=25/27
1)((x+y)/(x-y)-(x²-xy+y²)/(x²+xy+y²)=
=[(x+y)(x²+xy+y²)-(x-y)(x²-xy+y²)/[(x-y)(x²+xy+y²)]=
=(x³+x²y+xy²+xy²+x²y+y³-x³+x²y-xy²=x²y-xy²+y³)/(x³-y³)=
=(4x²+2y³)/(x³-y³)=2y(2x²+y²)/(x³-y³)
2)x(y³-x³)/[y(y²-2x²)(y²+2x²)*2y(2x²+y²)/(x³-y³)=-2x/(y²-2x²)=2x/(2x-y)
1. 15 3/4*2/9 = 63/4*2/9 = 7/2 = 3 1/2
2. 3 1/8:5/3 = 25/8:5/3 = 25/8*3/5 = 15/8 = 1 7/8
3. 14:2/7 = 14:2*7 = 7*7 = 49
49-5 7/10 = 43 3/10
4. 4 2/5*4/11 = 22/5*4/11 = 8/5
3 1/5:8/5 = 16/5*5/8 = 2
5. 21*2/3 = 14
20:2/5 = 20:2*5 = 50
14/50 = 7/25