The decrease of the decimal rate -1.05 mm/year can be rounded to -1. You don’t need to round 2.48 because you’re multiplying by -1. Since -1.05 is negative and rounded to a greater value, the estimate could be adjusted to a slightly lesser value, maybe -2.5 or -2.6.
Matea recorded that water levels in one part of the river fell 1.05 millimeters per year for 2.48 years. Describe how you could estimate the total variation in water level.