whenever you get charged for a phone service, you'd notice it usually says "so many hrs for so much money", but in short is just the quotient of each unit, namelhy either hr/$ or $/hr.
the first company charges $10/3.5hr, so the rate is their quotient, approximately $2.86/hr, namely $2.86 per hour.
the second company charges $1.25/(1/2)hr, so their quotient is $2.5/hr, namely $2.5 per hour.
