Provided Data:
Assuming a common volume unit denoted by \( x \), the weights are calculated as follows:
Weight of A = \( 3x \times 5 = 15x \)
Weight of B = \( 4x \times 2 = 8x \)
Weight of C = \( 7x \times 6 = 42x \)
The total weight of the alloy is the sum of individual weights:
\[ 15x + 8x + 42x = 65x \]
Given that the total weight is 130 kg:
\[ 65x = 130 \]
Solving for \( x \):
\[ x = \frac{130}{65} = 2 \]
The weight of Metal C is determined by:
\[ \text{Weight of C} = 42x = 42 \times 2 = \boxed{84 \text{ kg}} \]