\({2 \over 4 x} - {5 \over 4 x} = -{3 \over 4 x}\)

\({3 \over a} - {4 \over 2 a} = {6 \over 2 a} - {4 \over 2 a} = {2 \over 2 a} = {1 \over a}\)

\({6 \over 4 a} + {7 \over 3 b} = {18 b \over 12 a b} + {28 a \over 12 a b} = {18 b + 28 a \over 12 a b} = {9 b + 14 a \over 6 a b}\)

\(8 - {4 \over 7 x} = {8 \over 1} - {4 \over 7 x} = {56 x \over 7 x} - {4 \over 7 x} = {56 x - 4 \over 7 x}\)

\({7 p \over q} + {8 \over 3 q} = {21 p \over 3 q} + {8 \over 3 q} = {21 p + 8 \over 3 q}\)

\({2 p \over p} = {2 \over 1} = 2\)

\({x \over 4 x} = {1 \over 4}\)

\({-20 a \over 32 a} = -\frac{5}{8}\)

\({20 a \over -4 a} = -5\)

\({-15 x y \over 24 x z} = -{5 y \over 8 z}\)

\({-10 y \over 18 x y} = -{5 \over 9 x}\)

\({4 a b c \over -2 b c} = -2 a\)

\({4 p q \over q} - {5 p r \over r} = 4 p - 5 p = -p\)

\(4 p - {9 \over 2 p} = {4 p \over 1} ⋅ {2 p \over 2 p} - {9 \over 2 p} = {8 p^{2} \over 2 p} - {9 \over 2 p} = {8 p^{2} - 9 \over 2 p}\)

\({7 y \over 5 x} + {6 x \over 9 y} = {63 y^{2} \over 45 x y} + {30 x^{2} \over 45 x y} = {30 x^{2} + 63 y^{2} \over 45 x y} = {10 x^{2} + 21 y^{2} \over 15 x y}\)

\({7 \over a} ⋅ {4 \over b} = {28 \over a b}\)

\({a \over 7} ⋅ -{9 \over b} = -{9 a \over 7 b}\)

\(-{4 \over 3} ⋅ x = -{4 x \over 3}\)

\({7 q \over p} ⋅ {p - 5 \over 3} = {7 q (p - 5) \over 3 p} = {7 p q - 35 q \over 3 p}\)

\({8 \over x} : {7 \over y} = {8 \over x} ⋅ {y \over 7} = {8 y \over 7 x}\)

\({1 \over 9} : x = {1 \over 9} : {x \over 1} = {1 \over 9} ⋅ {1 \over x} = {1 \over 9 x}\)

\(-{7 \over 6} : {a - 5 b \over b} = -{7 \over 6} ⋅ {b \over a - 5 b} = -{7 b \over 6 (a - 5 b)} = -{7 b \over 6 a - 30 b}\)

\({9 a \over 4} + {a - 2 \over 7} = {63 a \over 28} + {4 (a - 2) \over 28} = {63 a + 4 (a - 2) \over 28} = {67 a - 8 \over 28}\)

\({-9 x + 5 \over 7 x - 4} + 6 = {-9 x + 5 \over 7 x - 4} + {6 (7 x - 4) \over 7 x - 4} = {-9 x + 5 + 6 (7 x - 4) \over 7 x - 4} = {-9 x + 5 + 42 x - 24 \over 7 x - 4} = {33 x - 19 \over 7 x - 4}\)