ayuda por f AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAÀAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
![ayuda por f AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAÀAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA class=](https://es-static.z-dn.net/files/d19/2db1d2d926b2c992a206587d523a2841.jpg)
Explicación paso a paso:
5 4 2 x
2 7
---------
* 7 9 4
* 9 4
----------
* 4 6 3 4
7xc termina en 4
7xb + 1 que llevas +4 termina en 3
7xa +2 que llevas mas + 9 termina en 6
Solo eso
abc = 542
abc - bca
542 - 425 = 117