Numerators will be equal after the multiplication.
The answer is -4 + 2 + -0.25 + 0.5.
Answer:

Step-by-step explanation:
Given
x ----- y
0.5. --- 0.8
1. --- 1.6
3.--- 4.8
25. --- 40
Required
Determine the constant of proportionality
This can be calculated using the following formula:
; Where r is the constant of proportionality;
Solve for r

When x = 0.5; y = 0.8


When x = 1; y =1.6


When x = 3; y = 4.8


When x = 25; y = 40


Notice that the value of r is constant throughout;
Hence:
