C-11-Q038mediumsingle_mcqa:b=c:da:b=c:da:b=c:d হলে a−ba+b=?\dfrac{a-b}{a+b} = ?a+ba−b=?ac−dc+d\dfrac{c-d}{c+d}c+dc−dbc+dc−d\dfrac{c+d}{c-d}c−dc+dca−bc−d\dfrac{a-b}{c-d}c−da−bda+bc+d\dfrac{a+b}{c+d}c+da+b