I am trying to find a macro that will solve the following equation:

y = 1.5*A*(x^(7/3)-x^(5/3))*(1+0.75*(B-4)*(x^(2/3)-1))

y and x will be determined from experimental data. A and B are the values to be solved for. I know that the equation can be made simpler if the value for x is replaced with x^(1/3). Any help that could be provided would be greatly appreciated.