\({7 \over 8 a} - {9 \over 8 a} = -{2 \over 8 a} = -{1 \over 4 a}\)

\({7 \over x} + {6 \over 4 x} = {28 \over 4 x} + {6 \over 4 x} = {34 \over 4 x} = {17 \over 2 x}\)

\({6 \over 7 p} - {5 \over 3 q} = {18 q \over 21 p q} - {35 p \over 21 p q} = {18 q - 35 p \over 21 p q}\)

\(3 - {9 \over 2 x} = {3 \over 1} - {9 \over 2 x} = {6 x \over 2 x} - {9 \over 2 x} = {6 x - 9 \over 2 x}\)

\(6 a - {8 \over 9 a} = {6 a \over 1} ⋅ {9 a \over 9 a} - {8 \over 9 a} = {54 a^{2} \over 9 a} - {8 \over 9 a} = {54 a^{2} - 8 \over 9 a}\)

\({3 x \over y} + {4 \over 7 y} = {21 x \over 7 y} + {4 \over 7 y} = {21 x + 4 \over 7 y}\)

\({6 b \over 8 a} + {3 a \over 2 b} = {6 b^{2} \over 8 a b} + {12 a^{2} \over 8 a b} = {12 a^{2} + 6 b^{2} \over 8 a b} = {6 a^{2} + 3 b^{2} \over 4 a b}\)

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

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

\({6 a \over 9 a} = \frac{2}{3}\)

\({4 a \over 2 a} = 2\)

\({-16 a b \over -18 a c} = {8 b \over 9 c}\)

\({25 y \over 45 x y} = {5 \over 9 x}\)

\({16 p q r \over 2 q r} = 8 p\)

\({2 x y \over y} - {4 x z \over z} = 2 x - 4 x = -2 x\)

\({5 \over x} ⋅ {6 \over y} = {30 \over x y}\)

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

\({4 \over 3} ⋅ a = {4 a \over 3}\)

\({9 \over a} : {5 \over b} = {9 \over a} ⋅ {b \over 5} = {9 b \over 5 a}\)

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

\({4 a \over 7} + {a - 6 \over 5} = {20 a \over 35} + {7 (a - 6) \over 35} = {20 a + 7 (a - 6) \over 35} = {27 a - 42 \over 35}\)

\({5 a + 6 \over -2 a + 8} - 9 = {5 a + 6 \over -2 a + 8} + {-9 (-2 a + 8) \over -2 a + 8} = {5 a + 6 - 9 (-2 a + 8) \over -2 a + 8} = {5 a + 6 + 18 a - 72 \over -2 a + 8} = {23 a - 66 \over -2 a + 8}\)

\({9 p^{2} - 3 p + 60 \over 3 p} = {9 p^{2} \over 3 p} - {3 p \over 3 p} + {60 \over 3 p} = 3 p - 1 + {20 \over p}\)

\({6 x^{2} - 5 x + 9 \over x^{2}} = {6 x^{2} \over x^{2}} - {5 x \over x^{2}} + {9 \over x^{2}} = 6 - {5 \over x} + {9 \over x^{2}}\)