Question

after singing for a few minutes the soloist rejoins the choir a second choir, consist of 90 additional singers then joins in each group of 10 singers sings with the same intensity as the first 10 person choir now how many decibels of sound intensity as the first 10 person choir now how many decibels of sound intensity are being produced

Answer 1

If the soloist produces "x" decibels and the 10-person choir produces "y" decibels, combined they will produce "x+y" decibels. 

The second choir has 90 additional singers, we base our description on the first choir. If a 10-person choir produces "x+y" decibels, then the 90 person choir produces 10 (x+y) decibels.