For explanatory purposes here is a very long winded answer:
Suppose that the starting sales volume is X, and the starting price is P.
Starting Revenue: XP
You are told that the new sales volume = (2/3) * X
You are told that the new sales price = 1.14P
So the New total revenue is (2/3)*1.14 * XP = 0.76XP
If the new revenue is 0.76XP, and the starting revenue is XP.....the percentage change in revenue is
As you get experienced, you may be able to do these with much less working. eg, note that revenue is proprtional to volume and price. So there is a 33.3333% drop followed by a 14% increase. overall Change = (2/3)*(1.14) - 1.