\({3 \over 4 x} - {7 \over 4 x} = -{4 \over 4 x} = -{1 \over x}\)

\({6 \over a} + {8 \over 3 a} = {18 \over 3 a} + {8 \over 3 a} = {26 \over 3 a}\)

\({6 \over 2 p} + {4 \over 7 q} = {42 q \over 14 p q} + {8 p \over 14 p q} = {42 q + 8 p \over 14 p q} = {21 q + 4 p \over 7 p q}\)

\(9 + {5 \over 2 x} = {9 \over 1} + {5 \over 2 x} = {18 x \over 2 x} + {5 \over 2 x} = {18 x + 5 \over 2 x}\)

\({7 a \over b} - {4 \over 6 b} = {42 a \over 6 b} - {4 \over 6 b} = {42 a - 4 \over 6 b} = {21 a - 2 \over 3 b}\)

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

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

\({-6 a \over -27 a} = \frac{2}{9}\)

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

\({10 p q \over -45 p r} = -{2 q \over 9 r}\)

\({-20 y \over 28 x y} = -{5 \over 7 x}\)

\({-6 x y z \over 3 y z} = -2 x\)

\({4 a b \over b} + {3 a c \over c} = 4 a + 3 a = 7 a\)

\(7 x - {4 \over 5 x} = {7 x \over 1} ⋅ {5 x \over 5 x} - {4 \over 5 x} = {35 x^{2} \over 5 x} - {4 \over 5 x} = {35 x^{2} - 4 \over 5 x}\)

\({8 b \over 9 a} + {4 a \over 6 b} = {16 b^{2} \over 18 a b} + {12 a^{2} \over 18 a b} = {12 a^{2} + 16 b^{2} \over 18 a b} = {6 a^{2} + 8 b^{2} \over 9 a b}\)

\({4 \over p} ⋅ {5 \over q} = {20 \over p q}\)

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

\(-{2 \over 9} ⋅ x = -{2 x \over 9}\)

\({2 q \over p} ⋅ {p - 6 \over 5} = {2 q (p - 6) \over 5 p} = {2 p q - 12 q \over 5 p}\)

\({6 \over x} : {4 \over y} = {6 \over x} ⋅ {y \over 4} = {6 y \over 4 x} = {3 y \over 2 x}\)

\({4 \over 9} : x = {4 \over 9} : {x \over 1} = {4 \over 9} ⋅ {1 \over x} = {4 \over 9 x}\)

\(-{1 \over 5} : {a + 9 b \over b} = -{1 \over 5} ⋅ {b \over a + 9 b} = -{b \over 5 (a + 9 b)} = -{b \over 5 a + 45 b}\)

\({a \over 2} + {a - 7 \over 9} = {9 a \over 18} + {2 (a - 7) \over 18} = {9 a + 2 (a - 7) \over 18} = {11 a - 14 \over 18}\)

\({7 a + 6 \over 2 a - 4} - 3 = {7 a + 6 \over 2 a - 4} - {3 (2 a - 4) \over 2 a - 4} = {7 a + 6 - 3 (2 a - 4) \over 2 a - 4} = {7 a + 6 - 6 a + 12 \over 2 a - 4} = {a + 18 \over 2 a - 4}\)