Упростите выражениеееееееееееееееее

▪а)

$\frac{2}{3 {x}^{2} {y}^{3} } - \frac{3}{5 {x}^{3} {y}^{2} } = \frac{2 \times 5x - 3 \times 3y}{15 {x}^{3} {y}^{3} } = \frac{10x - 9y}{15 {x}^{3} {y}^{3} }$

▪б)

$\frac{1}{y - 3} - \frac{6}{ {y}^{2} - 9 } = \frac{y + 3 - 6}{ {y}^{2} - 9 } = \frac{y - 3}{(y - 3)(y + 3)} = \frac{1}{y + 3}$

▪в)

$- \frac{3}{c - d} + \frac{4c - 4d}{ {c}^{2} - 2cd + {d}^{2} } = - \frac{3(c - d) + 4(c - d)}{ {(c - d)}^{2} } = - \frac{(c - d)(3 + 4)}{ {(c - d)}^{2} } = - \frac{7}{c - d}$

▪г)

$\frac{5}{4a + 8} - \frac{1}{3a + 6} = \frac{5}{4(a + 2)} - \frac{1}{3(a + 2)} = \frac{15 - 4}{12(a + 2)} = \frac{11}{12(a + 2)} = \frac{11}{12a + 24}$

▪д)

$\frac{1}{ab - {b}^{2} } - \frac{1}{ {a}^{2} - ab} = \frac{1}{b(a - b)} - \frac{1}{a(a - b)} = \frac{a - b}{ab(a - b)} = \frac{1}{ab}$