Find the midpoint of (1,-4) and (7,1) to find the rest stop. To do this add the x values and divide by 2, then add the y values and divide by 2. (4,-1.5) is the midpoint.
To find the distance, use the distance formula then multiply the result by 5.38. The distance is 42 miles
The base price of the iphone is $350 and additiobal charge of a month is $67. So additional charge for p months is $67p.
Determine the equation for total cost of iphone after p momths.