Fix grammar errors in this sentence: As the average cost of production declined steadily, radio set was mass produced leading to the birth of radio broadcasting.
The average cost of production of the, which is the most expensive radio set, was 100000000000000000000000000000000000000000000000000000000000000000000000000000000
The average cost of production of the, which was the most expensive in the world, was 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,