SOLUTION: Hi the average mass of 3 bags A B C when they are full is 38kg. When all the items from A are taken out the average mass of the 3 bags is 30kg.the mass of the items from B and C

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Question 1099546: Hi
the average mass of 3 bags A B C when they are full is 38kg. When all the items from A are taken out the average mass of the 3 bags is 30kg.the mass of the items from B and C is in the ratio of 7:3. If the mass of the items in B is 20kg heavier than the items in C, what is the total empty mass of the 3 bags.
thanks
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let m be the mass of the 3 bags empty.
Let A be the mass of the items in bag A and so on.
%28m%2BA%2BB%2BC%29%2F3=38
m%2BA%2BB%2BC=154
.
.
B%2FC=7%2F3
3B=7C
.
.
.
B=20%2BC
Substituting,
3%2820%2BC%29=7C
60%2B3C=7C
4C=60
C=15
and
3B=7%2815%29
B=7%285%29
B=35
So then when A=0,
%28m%2BB%2BC%29%2F3=30
m%2BB%2BC=90
m%2B35%2B15=90
m=40kg