depinde unde e "_" in dreptul pimei sau celei de a doua linii de fractie
cred ca e asa
140
___
13 21
_____ - ____
6 6
ca asa e mai usor, am o data acelasi numitor
140
____ - 21
13 140-21*13 140-273
____________ = _____________ = ____________ =-133/78
6 13*6 78
