3c - 2d = 2 / × ( - 1 ) ;
You obtain -3c + 2d = - 2 ;
But, +3c + 4d = 30 ;
_______________(+)
/ 6d = 28 ;
d = 28 / 6 = 14 / 3 ;
Finally, 3c - 2 * ( 14 /3 ) = 2 ;
3c - 28 / 3 = 2 ;
9c / 3 - 28 / 3 = 6 / 3 ;
9c - 28 = 6 ;
9c = 6 + 28 ;
9c = 34 ;
c = 34 / 9 ;
