.50 - x / x = 3.20e-1

I need to solve for x. I was going to do .50 X 3.20e-1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help.

You probably meant

(.50 - x)/x = 3.2 e^-1= 3.2/e
crossmultiply ...
.50 - x = (3.2/e)x
(3.2/e)x + x = .5
x(3.2/e + 1)
x = .5/(3.2/e + 1)
multiply by e/e
= .5e/(3.2 + e)
multiply by 10/10
= 5e/(32 + 10e)