$$a = \frac{n*\sum_{i = 1}^{n}{\left( x_{i}*y_{i} \right) -}\sum_{i = 1}^{n}{x_{i}*\sum_{i = 1}^{n}y_{i}}}{n*\sum_{i = 1}^{n}x_{i}^{2} - {(\sum_{i = 1}^{n}{x_{i})}}^{2}}$$

$$b = \frac{\sum_{i = 1}^{n}y_{i}}{n} - \frac{\sum_{i = 1}^{n}{x_{i}*a}}{n}$$

PRÓG RENTOWNOŚCI

Marża: $mb = c - kz = \frac{\text{MB}}{q}$ MB = P − KZ

Ilościowy $q = Q_{0} = \frac{\text{KS}}{c - kz} = \frac{\text{KS}}{\text{mb}}$

Wartościowy: $S_{0} = c*Q_{0} = c*\frac{\text{KS}}{c - kz} = c*\frac{\text{KS}}{\text{mb}}$

WSKAŹNIK MARŻY BRUTTO

$$W_{\text{mb}} = \frac{\text{mb}}{c} = \frac{\text{MB}}{P}$$