\({8 \over 5 a} + {7 \over 5 a} = {15 \over 5 a} = {3 \over a}\)

\({5 \over x} + {6 \over 7 x} = {35 \over 7 x} + {6 \over 7 x} = {41 \over 7 x}\)

\({7 \over 5 p} - {2 \over 3 q} = {21 q \over 15 p q} - {10 p \over 15 p q} = {21 q - 10 p \over 15 p q}\)

\(7 + {4 \over 9 x} = {7 \over 1} + {4 \over 9 x} = {63 x \over 9 x} + {4 \over 9 x} = {63 x + 4 \over 9 x}\)

\({2 a \over b} - {4 \over 7 b} = {14 a \over 7 b} - {4 \over 7 b} = {14 a - 4 \over 7 b}\)

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

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

\({10 x \over -45 x} = -\frac{2}{9}\)

\({18 p \over 2 p} = 9\)

\({-20 a b \over 36 a c} = -{5 b \over 9 c}\)

\({-28 b \over 36 a b} = -{7 \over 9 a}\)

\({10 x y z \over -5 y z} = -2 x\)

\({6 a b \over b} + {2 a c \over c} = 6 a + 2 a = 8 a\)

\(8 x + {7 \over 2 x} = {8 x \over 1} ⋅ {2 x \over 2 x} + {7 \over 2 x} = {16 x^{2} \over 2 x} + {7 \over 2 x} = {16 x^{2} + 7 \over 2 x}\)

\({3 q \over 6 p} - {7 p \over 5 q} = {15 q^{2} \over 30 p q} - {42 p^{2} \over 30 p q} = {-42 p^{2} + 15 q^{2} \over 30 p q} = {-14 p^{2} + 5 q^{2} \over 10 p q}\)

\({7 \over a} ⋅ -{5 \over b} = -{35 \over a b}\)

\({a \over 5} ⋅ {6 \over b} = {6 a \over 5 b}\)

\(-{6 \over 7} ⋅ x = -{6 x \over 7}\)

\({9 y \over x} ⋅ {x - 3 \over 8} = {9 y (x - 3) \over 8 x} = {9 x y - 27 y \over 8 x}\)

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

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

\({8 \over 7} : {p + 2 q \over q} = {8 \over 7} ⋅ {q \over p + 2 q} = {8 q \over 7 (p + 2 q)} = {8 q \over 7 p + 14 q}\)

\({4 x \over 9} + {x - 6 \over 2} = {8 x \over 18} + {9 (x - 6) \over 18} = {8 x + 9 (x - 6) \over 18} = {17 x - 54 \over 18}\)

\({5 a - 6 \over -7 a + 4} + 3 = {5 a - 6 \over -7 a + 4} - {-3 (-7 a + 4) \over -7 a + 4} = {5 a - 6 + 3 (-7 a + 4) \over -7 a + 4} = {5 a - 6 - 21 a + 12 \over -7 a + 4} = {-16 a + 6 \over -7 a + 4}\)