Complex sentence: Over the course of 1904 Formby purchased the singing rights for 57 numbers, more than his normal annual number of between 10 and 20; the average cost of his songs was around a guinea.
Split into simpler sentences: Over the course of 1904 Formby purchased the singing rights for 57 numbers, more than his normal annual number of between 10 and 20. The average cost of his songs was around a guinea.