If the first number is 20% less than the third number and the ratio of the second to the third number is 7 : 10, then the average of the first and the third number is how much per cent more than the second number?

Given:
First number is 20% less than the third number.
Ratio of the second to the third number = 7 : 10
Formula Used:

Solution
Let the third number be 10x and second number be 7x.
If first number is 20% less than the third number
then
First Number = 10x - 20% of 10x = 8x

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