An app had 60,000 users in June. During July it lost 15% of them and signed up 12,000 new users. By what per cent did its user count change over July?

It lost 15% of 60,000 = 9,000, dropping to 51,000, then added 12,000 to reach 63,000. The change over July is (63000 - 60000)/60000 = 3000/60000 = 0.05, a rise of 5%. 'A rise of 20%' counts only the 12,000 signed up and forgets the users lost. 'A fall of 15%' quotes only the loss. 'A rise of 23.53%' is 12000/51000, measuring the gain against the reduced mid-month figure instead of against the June count the question asks about.