a) 2/15-x = 3/10
<=> 45 - 3x = 20
<=> 3x = 45 - 20
<=> 3x = 25
<=> x = 25 : 3
<=> x = 25/3
Vậy x = 25/3
b) ( 10 - 4x ) + 120/23 = 17
<=> ( 10 - 4x ) + 120/8 = 17
<=> ( 10 - 4x ) + 15 = 17
<=> 10 - 4x = 17 - 15
<=> 10 - 4x = 2
<=> 4x = 10 - 2
<=> 4x = 8
<=> x = 8 : 4
<=> x = 2
Vậy x = 2