a,b,c,d.. rata2 ab=50, bc=75, cd=70, berapakah ad???, #pakai cara+jelaskan

Rata rata ab = 50 , bc = 75 , cd = 70

(a+b)/2 = 50
a + b = 100

(b+c)/2 = 75
b + c = 150

(c+d)/2 = 70
c + d = 140

a + d = ........

a + b + _ = 100
_ + b + c = 150 –
--------------------------
a ___- c = - 50

a - c + _ = -50
_+ c + d = 140 +
--------------------------
a __+ d = 90

a + d = 90

Jadi, jawabannya 90
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