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22/15 : 13/12 = x : 13/11 solito prodotto in croce 22/15*13/11 = 13x/12 26/15*12 = 13x x = 24/15 = 8/5

Seconda media

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$\left(\dfrac{2}{3}+\dfrac{4}{5}\right) : \left(\dfrac{1}{3}+\dfrac{3}{4}\right) = x : \left(2-\dfrac{9}{11}\right)$

$\left(\dfrac{10+12}{15}\right) : \left(\dfrac{4+9}{12}\right) = x : \left(\dfrac{22-9}{11}\right)$

$\dfrac{22}{15} : \dfrac{13}{12} = x : \dfrac{13}{11}$

$x= \dfrac{\cancel{22}^2}{15}·\dfrac{13}{\cancel{11}_1} : \dfrac{13}{12}$

$x= \dfrac{2}{15}·\dfrac{\cancel{13}^1}{1}·\dfrac{12}{\cancel{13}_1}$

$x= \dfrac{2}{\cancel{15}_5}·\dfrac{\cancel{12}^4}{1}$

$x= \dfrac{2}{5}·4$

$x= \dfrac{8}{5}$