-1/4X+(-2/5-X)=-9/20

Question

-1/4X+(-2/5-X)=-9/20

Answer 1

--1/4x + ( - 2/5 - x) = - 9/20
-1/4x - 2/5 - x = - 9 /20
-1  1/4x = -9/20 + 2/5
-5/4x = -9/20 + 8/20
-5/4x = -1/20
x = -1/20 : (-5/4)
x = 1/20 * 4/5
x = 1/25 

Answer 2

-1/4x + (- 2/5 - x) = - 9/20 | * 20
20 * (-1/4x) + 20 * (- 2/5 - x) = 20 * (- 9/20)  (всё это сокращаем)
5 * (-x) + 4 * (-2 -x) = -9
5x - 8 - 4x = -9
5x - 4x = -9 + 8
x = -1
Ответ: x = -1