Solve for x

ohnonotmath:

It has been so long since my last math class I completely forgot how to do this. Solve for x
.30 = x(1) - (1 - x).15

I think...
.3 = x - (.15 - .15x)

so far, so good.
0.3 = x - (0.15 - 0.15x)
0.3 = x - 0.15 + 0.15x (When you multiply a bracket by a negative number everything inside the bracket changes sign. ) I can show you why if you ask me to.
0.3+0.15 = x - 0.15 + 0.15x +0.15
0.45 = 1x - 0.15x
0.45 = (1-0.15)x
0.45 = 0.85x
0.45/0.85 = x
x = 45/85
x = 9/17

Oh thanks so much!
Now that you mention it I do remember that you have to change all the signs in the brackets when multiplying by a -
I would have never remembered to factor out the x though (the 5th line in your work)
Thanks so much again