a. How can tax on Pfizer's income be negative? Does it mean Pfizer saved that much money or they received that much amount from the government in Cash?

b. What is the effective rate of tax for Pfizer? Can it be negative? Why?

c. Give us brief details of what sort of tax benefits and tax expenses impacted FY 2017's Provision/(benefit) for taxes on income?

Consolidated Statements of Income Pfizer Inc. and Subsidiary Companies Year Ended December 31, (MILLIONS, EXCEPT PER COMMON SHARE DATA) 2017 2016 2015 Revenues $ 52,546 $ 52,824 $ 48,851 Costs and expenses: Cost of sales (a) 12,329 9,648 11,240 14,784 (a) 14,837 14,809 7,657 7,872 7,690 4,758 4,056 3,728 487 1,724 1,152 Selling, informational and administrative expenses Research and development expenses (2) Amortization of intangible assets Restructuring charges and certain acquisition-related costs Other (income)/deductionsnet Income from continuing operations before provision/(benefit) for taxes on income Provision/(benefit) for taxes on income Income from continuing operations 1,315 3,655 2,860 8,351 8,965 12,305 (9,049) 21,353 1,123 1,990 7,229 6,975