Question 1165461
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Let x be that additional discount, expressed as a decimal.


Then you have this equation


    (1-0.25)*(1-0.15)*(1-x) = 1 - 0.45

or

    0.75*0.85*(1-x) = 0.55

    1 - x = {{{0.55/(0.75*0.85)}}} = 0.862745.


Hence, the additional chain discount should be  1 - 0.862745 = 0.137255 = 13.7255%    <U>ANSWER</U>
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Solved.