\({4 \over 2 a} + {7 \over 2 a} = {11 \over 2 a}\)

\({7 \over p} + {2 \over 5 p} = {35 \over 5 p} + {2 \over 5 p} = {37 \over 5 p}\)

\({6 \over 8 x} + {2 \over 9 y} = {54 y \over 72 x y} + {16 x \over 72 x y} = {54 y + 16 x \over 72 x y} = {27 y + 8 x \over 36 x y}\)

\(3 - {6 \over 5 a} = {3 \over 1} - {6 \over 5 a} = {15 a \over 5 a} - {6 \over 5 a} = {15 a - 6 \over 5 a}\)

\({9 x \over y} + {3 \over 4 y} = {36 x \over 4 y} + {3 \over 4 y} = {36 x + 3 \over 4 y}\)

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

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

\({-10 x \over -15 x} = \frac{2}{3}\)

\({-25 a \over 5 a} = -5\)

\({10 p q \over -15 p r} = -{2 q \over 3 r}\)

\({-16 y \over -36 x y} = {4 \over 9 x}\)

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

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

\(2 p + {9 \over 7 p} = {2 p \over 1} ⋅ {7 p \over 7 p} + {9 \over 7 p} = {14 p^{2} \over 7 p} + {9 \over 7 p} = {14 p^{2} + 9 \over 7 p}\)

\({9 b \over 5 a} - {4 a \over 6 b} = {54 b^{2} \over 30 a b} - {20 a^{2} \over 30 a b} = {-20 a^{2} + 54 b^{2} \over 30 a b} = {-10 a^{2} + 27 b^{2} \over 15 a b}\)

\({6 \over x} ⋅ -{9 \over y} = -{54 \over x y}\)

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

\(-{5 \over 2} ⋅ x = -{5 x \over 2}\)

\({6 y \over x} ⋅ {x - 2 \over 9} = {6 y (x - 2) \over 9 x} = {2 y (x - 2) \over 3 x} = {2 x y - 4 y \over 3 x}\)

\({7 \over p} : {5 \over q} = {7 \over p} ⋅ {q \over 5} = {7 q \over 5 p}\)

\({5 \over 9} : a = {5 \over 9} : {a \over 1} = {5 \over 9} ⋅ {1 \over a} = {5 \over 9 a}\)

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

\({x \over 5} + {x - 8 \over 3} = {3 x \over 15} + {5 (x - 8) \over 15} = {3 x + 5 (x - 8) \over 15} = {8 x - 40 \over 15}\)