Răspuns
Explicație pas cu pas:
a / b = 0,8(3) = ( 83 - 8 ) / 90 = 75 / 90 = 15 / 18 = 5/6
=> a / b = 5 / 6 = > 6 a = 5 b => b = 6 a / 5
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( b - a ) / ( a + b ) = 1 / 11
= ( 6 a / 5 - a ) / ( a + 6 a / 5 ) =
= ( 6 a / 5 - 5 a / 5 ) / ( 5 a / 5 + 6 a / 5 ) =
= ( a / 5 ) : (11 a / 5 ) =
= ( a / 5 ) x ( 5 / 11 a ) =
= 1 / 11