Data Sufficiency (DS) | Re: A group of 20 friends went out for lunch. Five of them spent $21 each

Total friends - 20
5 spend $ 21 each so total of 5 = 105
And remaining 15 spend $x less than average of entire group; so let average be A, so each of the 15 spend $(A-x)
So total spend of all 20 = 105 + 15(A-x)
All this information is provided to us. And we are asked if A = 12?
Let us examine statements

Statement 1
x = 3
Average = Sum/Number
A = 105 + 15(A-3) / 20
20A = 105 + 15A - 45
5A = 60
A = 12

SUFFICIENT

Statement 2
Total Spend is 240
Average = Total/Number = 240/20 =12

SUFFICIENT


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