Salut,
[tex]\dfrac{\overline{aabb}+\overline{bbaa}}{\overline{abab}}=\dfrac{1000a+100a+10b+b+1000b+100b+10a+a}{1000a+100b+10a+b}=\\\\=\dfrac{1111a+1111b}{1010a+101b}=\dfrac{1111(a+b)}{101(10a+b)}=\dfrac{11(a+b)}{10a+b}=\dfrac{10a+b+10b+a}{10a+b}=\\\\=\dfrac{\overline{ab}+\overline{ba}}{\overline{ab}}=1+\dfrac{\overline{ba}}{\overline{ab}}[/tex]
Green eyes.
