Make sure you are confident in calculating with negative numbers, which is a skill often needed to solve equations. To solve the equation, do the inverse operation. The inverse of multiplying by 12 is ...
The Canadian Journal of Statistics / La Revue Canadienne de Statistique, Vol. 22, No. 2 (Jun., 1994), pp. 219-231 (13 pages) We consider the problem of robust M-estimation of a vector of regression ...