How do I calculate this problem?
Corporations face the following corporate tax schedule:

Taxable Income... Tax on Base... Rate
$ 0 – $50,000... $ 0... 15%
$ 50,000 – $75,000... $ 7,500... 25%
$ 75,000 – $100,000... $ 13,750... 34%
$100,000 – $335,000... $ 22,250... 39%

Company Z has $80,000 of taxable income from its operations, $5,000 of interest income, and $30,000 of dividend income from preferred stock it holds in other corporations. What is Company Z's tax liability?
my working =Everything is fully taxable so = $80,000 + 5,000 + 30,000 = $115,000
what do I do from here?:confused:

First I'd caution you to check your book or background material regarding the taxability of those preferred dividends. The tax rates in your schedule suggest that the problem is set in the context of US federal tax law, and generally US corporations enjoy a partial break in the taxability of divvys earned on stock held in other domestic corporations. I'll bet your book mentions somewhere that such dividends are only ___% taxable, or equivalently that ___% of the dividends are excludable from taxation.

Once you've determined the corporation's taxable income--whether it's 115K or some other amount--you use the table to determine the total tax liability by...

1) Find which of the four brackets the total taxable income falls within.
2) Determine the excess for that bracket, which is the excess of the total taxable income, over the bracket's lower amount.
3) The total tax is then that bracket's given base amount, plus the given percentage for the bracket, as applied to the excess.

For example, if you determined the taxable income to be 80,000 you see that this falls within the third (75K - 100K) bracket. The total tax on the 80,000 would be 13,750 + (0.34 x 5,000) = 15,450.

$115,000 will be
22,250 + (0.39 x How do I get this?

To the 22,250 you add 39% of the amount by which 115,000 exceeds the lower end of the bracket (100,000).

i.e. 22,250 + (39% x 15,000)

First, did you confirm that the preferred dividends are fully taxable?

Thank you very much