If a and b are the original prices of car A and car B respectively
After the change their prices will be 1.2a and 0.8b
We need to find what percent of car A original price is the reduced price of car B i.e 0.8b/a *100
As per 1 increase price of car A is equal to the original price of car B i.e 1.2a=b from which we can calculate b/a and the required percentage so 1 alone is sufficient
As per 2 increase in price of car A was 5/6 the decrease in the price of car B i.e 0.2a = 5/6*(0.2b) from which we can calculate b/a and the required percentage so 2 alone is sufficient.
Answer should be D
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