Algebra
posted by Lisa .
ABC phone company charges $18 per month plus 7 cents per minute of phone calls. XYZ phone company charges $9 per month and 10 cents per minute of phone calls. How many minutes of phone calls should be made each month to make the costs for the two companies the same?

ABC = 0.07m + 18
XYZ = 0.10m + 9
you want ABC = XYZ, so
.07m + 18 = .1m + 9
7m + 1800 = 10m + 900
3m = 900
m = 300
So at 300 minutes the charge would be the same from each company