Let A=total amount of wages
W=avg wage Wd=avg difference between individual's wage and the avg wage
E[Wi]=W1+W2+...+Wn=W E[Wdi]=[(W1-W)+(W2-W)+...+(Wn-W)]/n=Wd
B/c A=W1+W2+...Wn= $ \sum_{i=1}^n W $
Let A=total amount of wages
W=avg wage Wd=avg difference between individual's wage and the avg wage
E[Wi]=W1+W2+...+Wn=W E[Wdi]=[(W1-W)+(W2-W)+...+(Wn-W)]/n=Wd
B/c A=W1+W2+...Wn= $ \sum_{i=1}^n W $