Explicación paso a paso:
(5/4-13/6).20/7+7/6=
(15-26)/12.20/7+7/6=
-11/12.20/7+7/6=
-220/84+7/6=
-110/42+7/6=
-55/21+7/6=
(-220+98)/84=
-122/84=
-61/42
