<=> ( 100 + 10x + 5 ) + ( 40 + x ) . 2 = 221
<=> ( 100 + 10x + 5 ) + ( 80 + 2x ) = 221
<=> ( 100 + 5 + 80 ) + ( 10x + 2x ) = 221
<=> 185 + 12x = 221
<=> x = ( 221 - 185 ) : 12
=> x = 36 : 12
=> x = 3
Vậy x = 3
<=> ( 100 + 10x + 5 ) + ( 40 + x ) . 2 = 221
<=> ( 100 + 10x + 5 ) + ( 80 + 2x ) = 221
<=> ( 100 + 5 + 80 ) + ( 10x + 2x ) = 221
<=> 185 + 12x = 221
<=> x = ( 221 - 185 ) : 12
=> x = 36 : 12
=> x = 3
Vậy x = 3
mk cug nhu Dinh Duc Hung,check nha