Sam is earning some money picking apples. She gets paid $10 plus $2 per kilogram of apples that she picks. If Sam earns $C for n kg of apples picked, complete the following.
a) Write a rule for C in terms of n.
b) Use your rule to find:
(i) the amount Sam earned after picking 9kg of apples.
(ii) the number of kilograms of apples Sam picked if she earned $57.