Answer:
$39,000
Explanation:
The tax t(x) on income x will be computed as ...
t(x) = 0.30(x -100,000) +0.20(100,000 -50,000) +0.10(50,000)
= 0.30x -100,000(0.30 -0.20) -50,000(0.20 -0.10)
= 0.30x -10,000 =5,000
= 0.30x -15,000
Then the tax on 180,000 is ...
t(180,000) = 0.30(180,000) -15,000 = 54,000 -15,000
t(180,000) = 39,000
The federal income tax for the year is $39,000.