Word problem with 2 variables

Question

Corey's phone bill is $88.50.  Phone company charges $39 for first 100 min And $.45 for each additional min.  How many hours were used?

Answer 1

m represents number of minutes

 

88.50 = 39 + 0.45m              subtract 39 from both sides

49.50 = 0.45m                      divide both sides by 0.45

110 = m

 

Corey spoke for 100 (base) plus 110 (additional) minutes

Corey spoke for 210 minutes of 3 hours and 30 minutes.