Each month, a phone company charges $30 for 500 minutes of talk time plus $0.45 for each additional minute. Write an expression to show the cost of the monthly bill.

  30 +0.45(m -500) . . . . for m > 500

Step-by-step explanation:

If talk time is "m" minutes, then the number of "additional minutes" is ...

   m -500

The cost of those is $0.45 each, so (in dollars), the charge for additional minutes is ...

   0.45(m -500)

The charge of $30 applies regardless of the number of minutes, so is added to the minutes charge. The total cost of a bill for talking more than 500 minutes is ...

   30 +0.45(m -500)

The cost for talking 500 minutes or less is simply 30.

b.) 160 miles on a 5 gallons car

step-by-step explanation:

240/10=24 miles/gallon

160/5=32 miles/gallon

30/1=30 miles/gallon

168/6= 28 miles/gallon

32 miles/gallon is the most amount, so this is the best.