Answer:
The answer to your question is:
9th term = 
Step-by-step explanation:
The factor is 1/5, then:


Answer:
x= 11
Step-by-step explanation:
(x-5)/(x+1) = 3/6
6x-30 = 3x+3
3x = 33
x = 11
156 is even or odd number
Even number, it is divisible by 2
in 12 key 5 black keys are appearing so consider x key will appear in 120 keys
120/x = 12/5
solving further,
x= 50
Answer - If the pattern shown continues, 50 black keys appear on a pipe organ with a total of 120 keys!