( x + 10 )/( x + 20 ) - x/( x + 10 ) = 1/20
( ( x + 10)² - x( x + 20 )) / ( x + 10 )( x + 20 ) = 1/20
( x² + 20x + 100 - x² - 20x ) / ( x² + 20x + 10x + 200 ) = 1/20
100 / ( x² + 30x + 200 ) = 1/20
x² + 30x + 200 = 2000
x² + 30x - 1800 = 0
D = 900 + 7200 = 8100 = 90²
x1 = ( - 30 + 90 ) : 2 = 30
x2 = ( - 30 - 90 ) : 2 = - 60
ОДЗ х ≠ ( - 20 ) ; ( - 10 )
ОТВЕТ 30 ; - 60