Answer:
<h2><em>
[2(x+y)-25]cm</em></h2>
Step-by-step explanation:
Let the height of their oldest sister isabella be z centimeters. Roger is x centimeters tall and Olivia is y centimeters tall.
If their oldest sister, Isabella, is 25 centimeters shorter than the double of the sum of Roger and Olivia's height, this can be expressed as shown;
First let us get the sum of Roger and Olivia's height;
The sum of Roger and Olivia's height = (x+y)cm
The double of the sum of their ages = 2* (x+y)cm = 2(x+y)cm
Now if Isabella, is 25 centimeters shorter than the double of the sum of their ages, the expression will be [2(x+y)-25]
<em>Since the height of isabella is z, the expression that model isabella's height will be expressed as z =[2(x+y)-25]cm</em>
