The average of a b c is 20 and that of b c d is 25 if d 30 then the value of a is ........

Quantitative Aptitude (CGL) Average

The average of a,b,c is 20 and that of b,c,d is 25; if d=30, then the value of a is

a + b + c =60; ------ eq.(i)
b + c + d = 75; -------------- eq.(ii)
subtract eq.(i) from eq.(ii)-
a – d = -15; => a = 30-15=15;

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