\({3 \over 9 x} - {8 \over 9 x} = -{5 \over 9 x}\)

\({2 \over x} + {9 \over 3 x} = {6 \over 3 x} + {9 \over 3 x} = {15 \over 3 x} = {5 \over x}\)

\({5 \over 4 a} - {8 \over 2 b} = {5 b \over 4 a b} - {16 a \over 4 a b} = {5 b - 16 a \over 4 a b}\)

\(4 - {9 \over 8 p} = {4 \over 1} - {9 \over 8 p} = {32 p \over 8 p} - {9 \over 8 p} = {32 p - 9 \over 8 p}\)

\(4 a - {7 \over 6 a} = {4 a \over 1} ⋅ {6 a \over 6 a} - {7 \over 6 a} = {24 a^{2} \over 6 a} - {7 \over 6 a} = {24 a^{2} - 7 \over 6 a}\)

\({5 p \over q} + {4 \over 7 q} = {35 p \over 7 q} + {4 \over 7 q} = {35 p + 4 \over 7 q}\)

\({4 y \over 7 x} + {5 x \over 6 y} = {24 y^{2} \over 42 x y} + {35 x^{2} \over 42 x y} = {35 x^{2} + 24 y^{2} \over 42 x y}\)

\({5 a \over a} = {5 \over 1} = 5\)

\({x \over 7 x} = {1 \over 7}\)

\({-12 a \over 16 a} = -\frac{3}{4}\)

\({15 a \over 3 a} = 5\)

\({40 p q \over 45 p r} = {8 q \over 9 r}\)

\({15 y \over -35 x y} = -{3 \over 7 x}\)

\({12 x y z \over 4 y z} = 3 x\)

\({5 a b \over b} + {6 a c \over c} = 5 a + 6 a = 11 a\)

\({2 \over x} ⋅ -{9 \over y} = -{18 \over x y}\)

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

\(-{5 \over 2} ⋅ x = -{5 x \over 2}\)

\({8 \over p} : {9 \over q} = {8 \over p} ⋅ {q \over 9} = {8 q \over 9 p}\)

\(-{4 \over 3} : a = -{4 \over 3} : {a \over 1} = -{4 \over 3} ⋅ {1 \over a} = -{4 \over 3 a}\)