Buying books II

This task is about working out how much different numbers of books cost.
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The four books Ian bought at the book sale cost $5.40, $3.95, $7.85, and $6.90.

Question 2Change answer

a)  How much did he pay altogether?
     $
b)  How much would the most expensive book and the cheapest book cost together?
     $
c)  What is the largest number of books Ian could buy for $10?