Respuesta :

crisforp
4( a + 2b ) = 4a + 4*(2b) = 4a + 8b;
3( 2a - b ) = 3*(2a) - 3b = 6a - 3b;
3( 2a - b ) + 6a - 7b = 6a - 3b + 6a - 7b = 6a + 6a -3b -7b = 12a - 10b;
Finally, 4a + 8b = 12a - 10b;
8b + 10b = 12a - 4a;
18b = 8a ;
9b = 4a.