I'm working on a problem and im unsure how to calculate the weighted average cost of capital.

The question states : Determine the weight on debt capital that should be used to calculate Zonk's weighted-average cost of capital:

A.21.7%

B.21%

C.50%

D.58.2%

It then gives you the following data :

Total assets

$7,460

Interest-bearing debt

$3,652

Average pretax borrowing cost

10.5%

Common equity:

Book value

$2,950

Market value

$13,685

Income tax rate

35%

Market equity beta

1.13