What single percentage change is equivalent to a 15% decrease followed by a 16% decrease?

Decrease of 28.6%.

Step-by-step explanation:

The multiplier for a increase of a% is 1 + a/100.

The multiplier for a decrease of b% is 1 - b/100.

Decrease of 15%

1 - 15/100 = 1 - 0.15 = 0.85

Decrease of 16%

1 - 16/100 = 1 - 0.16 = 0.84

Both:

0.85*0.84 = 0.714

Change:

The initial percentage is 100% = 1.

0.714 - 1 = - 0.286

Negative, so a decrease

The answer is a decrease of 28.6%.