Answer:
a) 10%
Explanation:
To be able to own both (20%), you must fall into both categories. You own a cellular mobile, and you own a landline. The 20% is within the 50% + 40%.
50% + 40% = 90%
Subtract 90% from the total amount:
100 - 90 = 10
A) 10% is your answer.
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