arithmetic operations in dataframe in Python

sales.Thu.mul(sales.perc_Bonus, fill_value=0)
sales.iloc[:, :-1].sum(axis = 1).mul(sales.perc_Bonus)
sales["Bonus"] = sales.iloc[:, :-1].sum(axis = 1).mul(sales.perc_Bonus)

titanic["no_relat"] = titanic.sibsp.add(titanic.parch)
titanic["YoB"] = titanic.age.sub(1912).mul(-1)

fx_rate = 1.1
titanic["EUR_fare"] = titanic.fare.div(fx_rate)

sales.iloc[:, :-2].sub(fixed_costs, fill_value = 0)
sales.iloc[:, :-2].mul(perc_Bonus, fill_value = 0)
sales.iloc[:, :-2].floordiv(lot_size, fill_value = 0).mul(bonus_per_lot).sum(axis = 1)