15 * x - x = 378
15 * x - x * 1 = 378
( 15 - 1 ) * x = 378
14 * x = 378
x = 378 : 14
x = 27
15 x x - x = 378
15 x 2x = 378
2x = 378 : 15
2x = 25,2
x = 25,2 : 2
x = 12,6
Vậy x = 12,6
15 * x - x = 378
x * (15 - 1) = 378
x * 14 = 378
x = 378 : 14
x = 27
15 * x - x = 378
15 * x - x * 1 = 378
( 15 - 1 ) * x = 378
14 * x = 378
x = 378 : 14
x = 27
15 * x - x = 378
15 * x - x * 1 = 378
( 15 - 1 ) * x = 378
14 * x = 378
x = 378 : 14
x = 27
15 * x - x = 378
x * (15 - 1) = 378
x * 14 = 378
x = 378 : 14
x = 27
15 * x - x = 378
= 15 * x - x * 1 = 378
= ( 15 - 1 ) * x = 378
= 14 * x = 378
= x = 378 : 14
x 27