Company B; the ratios of cost to weight are equivalent.
Step-by-step explanation:
Step 1:
In the equation, 
k is the constant of proportionality.
If the values are in accordance with , the values of k will be constant for all the values.
So we determine the values of k for both the companies and see which has a constant k.
If 
. In these tables, y is the total cost and x is the weight in lbs.
Step 2:
For company A,
when 
when 
when 
For company B,
when 
when 
when 
So company B has a constant value of 
.
When rounding, look to the next place to the right of what you are rounding to... for example if you are rounding to the nearest hundredth, look to the thousandths place to see if the hundredths place rounds up or down. Since your number, 615.44 stops on the hundredths place, the thousandths place is automatically zero, so your number stays the same.
615.44
