Question 59349
x=a+b-2ab 
subtract b from both sides
{{{x - b = a -2ab}}}
swap right & left
{{{a - 2ab = x - b}}}
factor out the a
{{{a*(1 - 2b) = x - b}}}
divide both sides by (1 - 2b)
{{{a = (x - b) / (1 - 2b)}}} answer