Assuming this is the equation you want to operate on:
[tex] v^{2} = (v_0)^{2} + 2\cdot a \cdot \Deltax [/tex]
[tex] 2\cdot a \cdot \Delta x = v^{2} - (v_0)^{2} [/tex]
[tex] a = \frac{v^{2} - (v_0)^{2}}{2\cdot \Delta x} [/tex]
Before final operation we have to assume that x is not equal to 0. :)