Hard algebra problem?? How do I isolate the variable

How would you solve for 'z'?

(z)(z)/(0.050-z) = 1.5 x 10^-3

Thanks!

Z times z is z^2
1.5 x 10^-3 means move the decimal point to the left 3 places, or 0.0015
Multiply both sides of the equation by (0.05-z)
Now you have z^2 = 0.0015(0.05-z)
Can you take it from there?

The answer is 7.