Given information:
- The ratio of time of return stroke to time of forward stroke of a shaping machine is 0.6.
- The stroke length is 25C mm.
- The machine makes double strokes per minute.

To find: The overall average speed of operation.

Let's break down the problem into smaller steps:

Step 1: Determine the time taken for one complete cycle.
- Since the ratio of time of return stroke to time of forward stroke is 0.6, the total time for one complete cycle can be expressed as 1 + 0.6 = 1.6 units of time.

Step 2: Convert the stroke length from mm to meters.
- 1 mm = 0.001 m
- Therefore, the stroke length is 25C * 0.001 = 0.025C m.

Step 3: Calculate the distance traveled in one complete cycle.
- The distance traveled in one complete cycle is twice the stroke length, as the machine makes double strokes per minute.
- Therefore, the distance traveled in one complete cycle is 2 * 0.025C m.

Step 4: Calculate the time taken for one complete cycle.
- The time taken for one complete cycle is given by the product of the total time for one complete cycle and the time taken for a single stroke.
- Since the machine makes double strokes per minute, the time taken for a single stroke is 1/2 of a minute.
- Therefore, the time taken for one complete cycle is 1.6 * (1/2) minute.

Step 5: Calculate the overall average speed of operation.
- The overall average speed of operation is given by the formula: Speed = Distance/Time.
- Therefore, the overall average speed of operation is (2 * 0.025C m) / (1.6 * (1/2) minute).

Step 6: Simplify the expression.
- The overall average speed of operation is (0.05C m) / (0.8 minute).

Step 7: Convert the speed to meters per minute.
- Since 1 m = 1000 mm, 1 minute = 60 seconds, and 1 C = 10 mm, we can convert the units as follows:
- (0.05C m) / (0.8 minute) = (0.05C * 10 mm) / (0.8 * 60 seconds) = (0.5C mm) / (48 seconds) = (0.5C * 0.001 m) / (48 * 60 seconds) = (0.0005C m) / (2880 seconds).

Step 8: Simplify the expression.
- The overall average speed of operation is (0.0005C m) / (2880 seconds).

Step 9: Convert the speed to meters per minute.
- Since 1 minute = 60 seconds, we can convert the units as follows:
- (0.0005C m) / (2880 seconds) = (0.0005C m) / (2880 * 60 seconds) = (0.0005C m) / (172800 seconds) = (0.0005C * 60 m) / (172800 * 60 seconds) = (0.03C m) / (172800 seconds).

Step 10: Simplify the