"22", "7" and "7,5" are the answers in order
Answer:
The weight of container C is 2.1kg.
Step-by-step explanation:
This question is solved using a system of equations.
I am going to say that:
x is the weight of container A.
y is the weight of container B.
z is the weight of container C.
The average weight of 3 containers A,B and C is 3.2kg.
This means that the total weight is 3*3.2 = 9.6kg. So

Container A is twice as heavy as container B.
This means that
.
Containers B is 400 g heavier than container C.
400g is 0.4kg. So
This means that
, or 
Replacing y and z as functions of x in the first equation:




Container C

The weight of container C is 2.1kg.
7(4)-9(130)
28-1170
answer: -942