y as subject of t=w(1-y)/y
t = w(1-y) / yMultiply each side by 'y': t y = w(1-y)Eliminate parentheses: t y = w - wyAdd 'wy' to each side: t y + w y = wFactor the left side: y (t + w) = wDivide each side by (t+w) y = w / (t + w)