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The average cost of a long-distance call in the USA in 1985 was 41 cents per minute, and the average cost of a long-distance call in the USA in 2005 was 7 cents per minute. Find the approximate percent decrease in the cost per minute of a long- distance call. (2007 AMC 8, Question \#6) 
Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Percentages Word Problems
The percent decrease is (the amount of decrease)/(original amount) the amount of decrease is $41-7=34$ so the percent decrease is $\frac{34}{41}$ which is about $(\mathbf{E}) 80 \textbackslash\%$ 