Answer:
The hourly decay rate is of 1.25%, so the hourly rate of change is of -1.25%.
The function to represent the mass of the sample after t days is 
Step-by-step explanation:
Exponential equation of decay:
The exponential equation for the amount of a substance is given by:

In which A(0) is the initial amount and r is the decay rate, as a decimal.
Hourly rate of change:
Decreases 26% by day. A day has 24 hours. This means that
; We use this to find r.



![\sqrt[24]{(1-r)^{24}} = \sqrt[24]{0.74}](https://tex.z-dn.net/?f=%5Csqrt%5B24%5D%7B%281-r%29%5E%7B24%7D%7D%20%3D%20%5Csqrt%5B24%5D%7B0.74%7D)



The hourly decay rate is of 1.25%, so the hourly rate of change is of -1.25%.
Starts out with 810 grams of Element X
This means that 
Element X is a radioactive isotope such that its mass decreases by 26% every day.
This means that we use, for this equation, r = 0.26.
The equation is:



The function to represent the mass of the sample after t days is 
Answer:
24 miles.
Step-by-step explanation:
Jackie traveled four times as many miles by bus as by foot. This means that the number of miles travelled by bus is 4 units, and the number of miles travelled by foot is 1 unit.
Jackie traveled three times as many miles by train as by bus. We know that the number of miles travelled by bus is 4 units, so the number of miles travelled by train is
units.
Total number of units: 

Divide 17:

The number of miles travelled by train is 12 units:

She travelled 24 miles by train.
53.67 to one decimal place is 53.7 since you round the .6 to the .7
Answer:
36 km
Step-by-step explanation:
60% of 60km
60/100
.6*60=36
36 km