jacquim compared the prices per month of four diffrent cell phone plans.
Cost
PLANS |100min 300min 500min 700min
companyA| $12 $36 $60 $84
CompanyB| $22 $36 $50 $64
CompanyC| $19 $37 $55 $73
CompanyD| $16 $36 $56 $76
Which phone company offers plans that have proportional relationships between the minutes and price?
A companyA
B companyB
C companyC
D companyD
Looks like A to me.
The prices are in the ratio 1:3:5:7, just like the times.