Question

(5x+7)-(8x+13)=9, прошу помогите! ​

Answer 1

(5x+7)-(8x+13)=9
5x+7-8x-13=9
5x-8x=9-7+13
-3x=15
X=15:-3
X=-5
Відповідь: -5.

Answer 2

(5х + 7) - (8х + 13) = 9

5х + 7 - 8х - 13 = 9

5х - 8х = 9 - 7 + 13

-3х = 15

х = 15 : (-3)

х = -5

- - - - - - - - - -

Проверка:

(5 · (-5) + 7) - (8 · (-5) + 13) = 9

(-25 + 7) - (-40 + 13) = 9

-18 - (-27) = 9

-18 + 27 = 9

9 = 9 - верно.