What is the lowest unit rate in minutes (the best deal)? Also write down which store has the best deal (I kind need to know :-D).
Store A: $25 for a 45 minute lesson.
Store B: $30 for a 1 hour lesson.
Store C: $45 for a 1.5 hour lesson.
Store D: $80 for three 1 hour lessons.

The answer is Store D.

Step-by-step explanation:

In order to find which has the lowest unit rate in minutes, we have to find how much it cost per minutes :

Store A,

45 mins = $25

1 min = $25/45

= $0.56 (2d.p)

Store B,

1 hr = $30

60 mins = $30

1 min = $30/60

= $0.50

Store C,

1.5 hr = $45

(60+30)mins = $45

90 mins = $45

1 min = $45/90

= $0.50

Store D,

three 1 hr lessons = 3hr lessons

3 hr = $80

(3×60)mins = $80

180 mins = $80

1 min = $80/180

= $0.44

By looking at the cost, we know that Store D has the lowest unit rate in minutes which is $0.44/min.