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5 + a = [tex] \frac{4}{5} [/tex] × ( 9 + a )

DAU COROANA


Răspuns :

5 + a = 4/5 * (9 + a)
5 + a = 36/5 + 4a/5
25 + 5a = 36 + 4a
5a - 4a = 36 - 25
a = 11

[tex]5+a = \dfrac{4}{5}\times(9+a) \Big|\cdot 5 \\ \\ 25+5a = 4\times(9+a) \\ \\ 25+5a = 36+4a \\ \\ 5a-4a = 36-25 \\ \\ \boxed{a = 11}[/tex]