\({7 \over 4x}+{9 \over 4x}={16 \over 4x}={4 \over x}\)

\({8 \over a}+{2 \over 5a}={40 \over 5a}+{2 \over 5a}={42 \over 5a}\)

\({7 \over 5a}-{2 \over 4b}={28b \over 20ab}-{10a \over 20ab}={28b-10a \over 20ab}={14b-5a \over 10ab}\)

\(4-{2 \over 3p}={4 \over 1}-{2 \over 3p}={12p \over 3p}-{2 \over 3p}={12p-2 \over 3p}\)

\({2x \over y}+{7 \over 5y}={10x \over 5y}+{7 \over 5y}={10x+7 \over 5y}\)

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

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

\({-15x \over 27x}=-\frac{5}{9}\)

\({10p \over -5p}=-2\)

\({-8ab \over -12ac}={2b \over 3c}\)

\({4y \over 10xy}={2 \over 5x}\)

\({12pqr \over 4qr}=3p\)

\({5ab \over b}+{3ac \over c}=5a+3a=8a\)

\(9a-{3 \over 7a}={9a \over 1}⋅{7a \over 7a}-{3 \over 7a}={63a^2 \over 7a}-{3 \over 7a}={63a^2-3 \over 7a}\)

\({5b \over 2a}+{8a \over 4b}={10b^2 \over 4ab}+{8a^2 \over 4ab}={8a^2+10b^2 \over 4ab}={4a^2+5b^2 \over 2ab}\)

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

\({x \over 2}⋅{3 \over y}={3x \over 2y}\)

\({2 \over 7}⋅p={2p \over 7}\)

\({2b \over a}⋅{a+3 \over 9}={2b(a+3) \over 9a}={2ab+6b \over 9a}\)

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

\(-{8 \over 9}:x=-{8 \over 9}:{x \over 1}=-{8 \over 9}⋅{1 \over x}=-{8 \over 9x}\)

\({7 \over 4}:{x+y \over y}={7 \over 4}⋅{y \over x+y}={7y \over 4(x+y)}={7y \over 4x+4y}\)

\({8a \over 3}+{a-7 \over 4}={32a \over 12}+{3(a-7) \over 12}={32a+3(a-7) \over 12}={35a-21 \over 12}\)

\({2p-3 \over -5p-9}+7={2p-3 \over -5p-9}-{-7(-5p-9) \over -5p-9}={2p-3+7(-5p-9) \over -5p-9}={2p-3-35p-63 \over -5p-9}={-33p-66 \over -5p-9}\)