Consider the reactions
(i) (CH3)2CH−CH2BrC2H5OH−−−−−→(CH3)2CH−CH2OC2H5+HBr
(ii) (CH3)2CH−CH2BrC2HSO−−−−−−→(CH3)2 CH CH2OC2H5+Br−
The mechanism of reactions (i) & (ii) are respectively