The total change in water level over three months, considering fractional changes, is
centimeters.
To find the total change in water level over the three-month period, add the changes for each month:
1. Month 1: -1 (multiplied by 3/4)

2. Month 2:

- No further modification needed for Month 2.
3. Month 3:

- No additional modification required for Month 3.
Now, summing up the changes:
![\[ -(3)/(4) + \left(-(1)/(28)\right) + \left(-(15)/(28)\right) \]](https://img.qammunity.org/2023/formulas/mathematics/middle-school/defxb490yldgf5lbxdb3ldolfnvoak09ag.png)
To combine these fractions, find a common denominator, which is 28 in this case:
![\[ -(21)/(28) + \left(-(1)/(28)\right) + \left(-(15)/(28)\right) \]](https://img.qammunity.org/2023/formulas/mathematics/middle-school/cmn5p1jgr2yvzgj42fpcifgp5lbz6yfa0w.png)
Combine the numerators:

The total change in water level for the three-month period is
centimeters.