13 times an unknown number added 72 equals - 23 times the unknown number

X=2

Step-by-step explanation:

Let the unknown number be x

13*x+72=-23*x

13x+72=-23x (collect like terms and add - 72 to both sides)

13x+72-72=-23x-72=13x=-23x-72 (collect like terms again and add + 23x to both sides)

13x+23x=-23x-72+23x=36x=-72

36x=-72 (divide both sides by the coefficient of x; 36 on both sides)

36x/36=-72/36

X=2.