Growco, a domestic corporation, is a manufacturer. Growco is planning to build a new production facility, and has narrowed down the possible sites for this new plant to either Happystan $($a low tax foreign country$)$ or Sadstan $($a high tax foreign country$).$ Growco will structure the new facility as a wholly$-$owned foreign subsidiary, Sproutco, and finance Sproutco solely with an equity investment. Growco projects that Sproutco's results during its first year of operations will be as follows:

Sales$-$ $$400,000$

Cost of goods sold $-(290,000)$

Selling, general and administrative expenses$-(60,000)$

Income before income taxe $-$ $$50,000$

Assume that the U$.$S$.$ corporate tax rate is $21\%,$ the Happystan rate is $10\%,$ and the Sadstan rate is $30\%.$ Further assume that neither Happystan nor Sadstan imposes withholding taxes on interest or royalty payments paid by a local subsidiary to its U$.$S$.$ parent company. Compute the total tax rate $($U$.$S$.$ plus foreign$)$ on Sproutco's profits under the following assumptions:

a$.$ The new production facility is located in Happystan.

b$.$ The new production facility is located in Sadstan.

c$.$ The new production facility is located in Sadstan, but Growco modifies its plans. Specifically, Growco will finance Sproutco with both debt and equity, such that Sproutco will pay Growco $$15,000$ of interest each year. Growco will also charge Sproutco an annual royalty of $$10,000$ for the use of Sproutco's patents and trade secrets$.$

What do the results of these various scenarios suggest regarding the differential tax costs of operating in low versus high tax countries?