Given:
Over the past 4 years, Grandpa Ernie's height decreased by a total of 2.4 cm.
It decreased by the same amount each year.
To find:
The change in Grandpa Ernie's height each year.
Solution:
Total change in Grandpa Ernie's height in past 4 years = -2.4 cm
Here, negative sign represents the decrease in height.
It decreased by the same amount each year.
So, change in each year is



Therefore, the change in Grandpa Ernie's height each year is -0.6 cm. It means, the Grandpa Ernie's height decreased by 0.6 cm each year.