Ten points for a step by step explanation of this problem

I really do not understand how to solve this problem with these variables. Please help me
0.270v^2/c^2=1-v^2/c^2
v=0.887c.
I really need to know how to get 0.887
I am getting 0.963 or 0.854. I am guessing. I do not even know the steps to solve for v.

Let Y = (v/c)^2.
The given equation simplified to
0.27Y = 1 - Y
1.27Y = 1
Y = 1/1.27 = 0.7874

Replacing Y with (v/c)^2,
(v/c)^2 = 0.7874
Taking the square root of both sides,
v/c = 0.887
or
v = 0.887c