Increase in spending in November: 30% x $1600
= 30/100 x $1600
Since his monthly salary is the same for both months, this means that however much he increases his spending by, he needs to decrease his savings by the same amount.
Therefore, his savings also decreased by $480. We know that this resulted in a 50% decrease in his savings from November to December.
50% of savings in November = Decrease in amount of savings = $480
100% of savings in November = $480 x 2