The tax liability for a married couple with taxable income of $87,312 is:

A. $18,068.
B. $16,599.
C. $14,081.
D. $14,078.

joint return both under 65 no credits, no deductions (very unusual), no retirement plan, no state taxes etc etc etc

http://www.taxbrain.com/taxcenter/taxcalculator/default.asp

$9,399

I did it on gross income.

$16,599
from tax tables
http://www.taxbrain.com/taxcenter/taxcalculator/default.asp

can you please show me the actual way without using this calculator?

I used tax tables

Tax Brackets 2011 Single Married Filing Jointly Head of Household

10% Bracket $0 – $8,500 $0 – $17,000 $0 – $12,150
15% Bracket $8,500 – $34,500 $17,000 – $69,000 $12,150 – $46,250
25% Bracket $34,500 – $83,600 $69,000 – $139,350 $46,250 – $119,400
28% Bracket $83,600 – $174,400 $139,350 – $212,300 $119,400 – $193,350
33% Bracket $174,400 – $379,150 $212,300 – $379,150 $193,350 – $379,150
35% Bracket $379,150+ $379,150+ $379,150+

Sorry, 14,081

from

http://www.irs.gov/pub/irs-pdf/i1040tt.pdf
or use above brackets
10% 0 to 17,000 --> $1700
15% 17k to 69 k --> $7800
25% 69k to 18312 --> $4578
1700+7800+4578 = 14,078 close to 14081 (tables not exact)