Respuesta :

idkwhy14

[tex] \frac{3}{10} + ( - \frac{4}{7} ) = [/tex]

[tex] \frac{3}{10} - \frac{4}{7} = [/tex]

3 x 7 = 21

10 x 4 = 40

10 x 7 = 70

[tex] = \frac{21 - 40}{70} [/tex]

[tex] = \frac{ - 19}{70} [/tex]

[tex] = - \frac{19}{70} [/tex]

So, the number that belongs in the green box is 19.

gmany

Answer:

[tex]\large\boxed{-\dfrac{19}{70}\to\boxed{19}}[/tex]

Step-by-step explanation:

[tex]\dfrac{3}{10}+-\dfrac{4}{7}=\dfrac{3}{10}-\dfrac{4}{7}\\\\\text{find the common denominator}\ LCD(10,\ 7)=70\\\\\dfrac{3}{10}=\dfrac{3\cdot7}{10\cdot7}=\dfrac{21}{70}\\\\\dfrac{4}{7}=\dfrac{4\cdot10}{7\cdot10}=\dfrac{40}{70}\\\\=\dfrac{21}{70}-\dfrac{40}{70}=\dfrac{21-40}{70}=-\dfrac{19}{70}[/tex]

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