a)=[m]\frac{3a}{8b}[/m];
б)=[m]\frac{y\cdot (y+1)}{y^2}=\frac{y+1}{y}[/m].
2.
а)=[m]\frac{12x-7+3x-2}{15x}=\frac{15x-9}{15x}=\frac{3\cdot (5x-3)}{15x}=\frac{5x-3}{5x}[/m];
б) =[m]\frac{a(x+y)}{xy^2}\cdot \frac{x^2y}{3(x+y)}=\frac{ax}{y}[/m].
3.
=[m]\frac{(y-3)^2}{(y-3)(y+3)}\cdot \frac{y(y+3)}{10(y-3)}=\frac{y}{10}[/m]
при y=70
о т в е т. 7