Question

помогите пожалуйста ​

Answer 1

1а) $\frac{15a(a-b)}{40b(a-b)}=\frac{3a}{8b}$

1б) $\frac{y^2+y}{y^2}=\frac{y(y+1)}{y^2}=\frac{y+1}y$

2а) $\frac{12x-7}{15x}+\frac{3x-2}{15x}=\frac{12x-7+3x-2}{15x}=\frac{15x-9}{15x}=\frac{5x-3}{5x}=1-\frac3{5x}$

2б) $\frac{ax+ay}{xy^2}\cdot\frac{x^2y}{3x+3y}=\frac{ax^2y(x+y)}{3xy^2(x+y)}=\frac{ax}{3y}$

3) $\frac{y^2-6y+9}{y^2-9}:\frac{10y-30}{y^2+3y}=\frac{(y-3)^2\cdot y(y+3)}{(y-3)(y+3)\cdot10(y-3)}=\frac y{10}$. При y=70: $\frac{70}{10}=7$