Answer: a) $149,100
Explanation:
The amount of common fixed cost that is not traceable to any of the individual divisions will be the difference between their two segment margins and the corporations net operating income because the fixed costs would have been subtracted from their segment contributions to find the Corporation's net operating income;
= GBI Margin + AFE Margin - Corporation net income
= 175,400 + 15,700 - 42,000
= $149,100