I think you meant the two <em>segments</em><em> </em>are identical, if so then:

Step-by-step explanation:
r-5r-6s+8s-15
-4r+2s-15
= 2s-4r-15
The constant of proportionality is 1.25 and its meaning is the soup price per can
Step-by-step explanation:
The diagram below shows a proportional relationship between the number of cans of soup and the price.
1st:
$3.75 for 3 cans
per can
2nd:
$6.25 for 5 cans
per can
If x is the number of cans and y is the price of x cans, then
This means the constant of proportionality is 1.25 and its meaning is the soup price per can