\({3 \over 9 x} + {7 \over 9 x} = {10 \over 9 x}\)

\({2 \over a} + {9 \over 8 a} = {16 \over 8 a} + {9 \over 8 a} = {25 \over 8 a}\)

\({2 \over 4 p} + {5 \over 9 q} = {18 q \over 36 p q} + {20 p \over 36 p q} = {18 q + 20 p \over 36 p q} = {9 q + 10 p \over 18 p q}\)

\(7 - {5 \over 6 a} = {7 \over 1} - {5 \over 6 a} = {42 a \over 6 a} - {5 \over 6 a} = {42 a - 5 \over 6 a}\)

\({9 x \over y} + {4 \over 7 y} = {63 x \over 7 y} + {4 \over 7 y} = {63 x + 4 \over 7 y}\)

\({3 x \over x} = {3 \over 1} = 3\)

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

\({-16 a \over 28 a} = -\frac{4}{7}\)

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

\({-12 p q \over -16 p r} = {3 q \over 4 r}\)

\({-8 b \over 10 a b} = -{4 \over 5 a}\)

\({35 x y z \over -5 y z} = -7 x\)

\({5 x y \over y} + {3 x z \over z} = 5 x + 3 x = 8 x\)

\(2 a - {4 \over 7 a} = {2 a \over 1} ⋅ {7 a \over 7 a} - {4 \over 7 a} = {14 a^{2} \over 7 a} - {4 \over 7 a} = {14 a^{2} - 4 \over 7 a}\)

\({2 b \over 3 a} - {8 a \over 6 b} = {4 b^{2} \over 6 a b} - {8 a^{2} \over 6 a b} = {-8 a^{2} + 4 b^{2} \over 6 a b} = {-4 a^{2} + 2 b^{2} \over 3 a b}\)

\({6 \over p} ⋅ {9 \over q} = {54 \over p q}\)

\({x \over 4} ⋅ -{9 \over y} = -{9 x \over 4 y}\)

\({2 \over 3} ⋅ x = {2 x \over 3}\)

\({6 b \over a} ⋅ {a - 9 \over 3} = {6 b (a - 9) \over 3 a} = {2 b (a - 9) \over a} = {2 a b - 18 b \over a}\)

\({3 \over a} : {5 \over b} = {3 \over a} ⋅ {b \over 5} = {3 b \over 5 a}\)

\({8 \over 3} : x = {8 \over 3} : {x \over 1} = {8 \over 3} ⋅ {1 \over x} = {8 \over 3 x}\)

\({2 \over 9} : {x - 4 y \over y} = {2 \over 9} ⋅ {y \over x - 4 y} = {2 y \over 9 (x - 4 y)} = {2 y \over 9 x - 36 y}\)

\({8 p \over 7} + {p + 3 \over 9} = {72 p \over 63} + {7 (p + 3) \over 63} = {72 p + 7 (p + 3) \over 63} = {79 p + 21 \over 63}\)

\({-5 x + 2 \over 8 x - 7} + 6 = {-5 x + 2 \over 8 x - 7} + {6 (8 x - 7) \over 8 x - 7} = {-5 x + 2 + 6 (8 x - 7) \over 8 x - 7} = {-5 x + 2 + 48 x - 42 \over 8 x - 7} = {43 x - 40 \over 8 x - 7}\)

\({a^{2} + 5 a + 9 \over 8 a^{2}} = {a^{2} \over 8 a^{2}} + {5 a \over 8 a^{2}} + {9 \over 8 a^{2}} = \frac{1}{8} + {5 \over 8 a} + {9 \over 8 a^{2}}\)