Salut/Hello!
Answer: 16,(6)% and it's a decrease
Explanation:
/ - fraction line
initial records = 120
after selling = 100
=> records sold = 120 - 100 = 20
We know that:
100% = 120/100 => 1% = 1.2/100
120 - 100 = 20
So we can find: 20 : 1.2 = 16,(6)%
Because 5% = 6 and 6 : 1.2 = 5%
So by knowing the amount of records sold and the percentage per record we divide them and find out the percentage of records sold.
I hope it'll be useful! :]