Final answer:
The decay factor (b) is 0.75, obtained by dividing the y-value at x=1 by the y-value at x=0. The exponential function is y = 16(0.75)^x.
Step-by-step explanation:
To find the decay factor (b), we use the given points (0,16) and (1,12). Since the decay is by a constant percentage, we divide the y-value at x=1 by the y-value at x=0, which gives us 12/16 or 0.75. Therefore, the decay factor is 0.75.
The exponential function representing the relationship is therefore y = 16(0.75)^x, where 16 is the initial amount (y-intercept) and 0.75 is the decay factor.