Answer:
The correct option is (c) 21.78
Explanation:
Given:
Sales = $450
Costs = $350
Increased sales = 450×1.1 = $495
Increased cost (in the same proportion) = 350×1.1 = $385
EBIT = Sales - cost
    = 495 - 385
    = $110
EAT = 110×(1-0.34)
    = $72.60
Retention Ratio = 30%
Addition to retained earnings = EAT × retention ratio
                       = 72.6 ×0.3
                       = $21.78
Therefore, addition to retained earnings is $21.78.