**Example 1 Question 1** - no calculation required

Total annual cost = annual membership + cost of p classes in a year = 25 + 20p

**Example 1 Question 2** - mental math

Cost of 5 classes is 20 x 5 = 100. Hence, total annual cost = 25 + 100 = 125

**Example 2** - mental math

Total books = existing books + 4 books per week for 7 weeks = 38 + 28 = 66