Well it is a simple percentage question that we have to solve.
As we know that William made 620 by baby sitting and we also know that he made 340 per cent more next year so we can simply calculate 340 per cent of 620 and then add that percentage value to 620 to calculate the final answer.
So 340 / 100 * 620 equals to 2108 so the final answer is 2108 + 620 which becomes 2728.