Let x = a number
3(6 - x) = -9
Divide both sides of equation by 3.
6 - x = -3
Subtract 6 on both sides of equation.
-x = -9
Divide both sides of equation by -1.
x = 9
The number is 9.
The difference between a number and six is [tex] x-6 [/tex]. Twice this difference is [tex] 2(x-6) [/tex]. If you want this difference to be negative, six, you have
[tex] 2(x-6)=-6 [/tex]
Divide both sides by 2:
[tex] x-6 = -3 [/tex]
Add 6 to both sides:
[tex] x = 3 [/tex]
