How to determine the induvidual partial slope coefficient under multiple regression model??

The individual partial slope coefficient can be determined by calculating the partial derivative of the regression equation with respect to the independent variable in question. This can be done by taking the derivative of the equation with respect to the independent variable, while holding all other independent variables constant. The resulting partial derivative is the individual partial slope coefficient.

The following two models were estimated to analyze the demand for chicken around

Mzumbe university campus.
I.Qc = 43.310 –15.298Pc –9.86Pb + 39.8Pf + 1.87Y.
Where Qc = quantity of chicken demanded in 2012.
Pc=price ofchicken.
Pb = price of beef.
Pf = price of fish.
Y=income.
a) Determine the induvidual partial slope coefficients