approximately where should it set the income tax rate, economics homework help

Description

Say that Thailand has a workforce of 35,709,487 people, each of whom earns an average salary of (equivalent USD) $8,630 annually. If the Thai government wants to raise $70 billion in tax revenue, approximately where should it set the income tax rate?
a.
5%
b.
15%
c.
23%
d.
29%