Tax : Questions return, gift

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CFAI Text V2

P.190~191, Accrual Equivalent Tax Rate
Can we apply formula (6) to Example 8 on P.188 in which r* & T* are used in formula (5) rather than r & tcg in formula (3a/b) ?

Reading 16 : EOC Q3B
Why rg = 0.1 ? It is not given ! rg is pre-tax return to the gift recipient as defind on the top of P.237. Shall we assume rg = re if rg is not given while re is given and vice versa ?