Which is the right answer?

Janie has $3. she earns $1.20 for each chore she does and can do fractions of chores. she wants to earn enough money to buy a cd for $13.50.

Which two fractions are equivalent to 24/84? 6/42 and 2/7 6/21 and 2/6 12/42 and 3/7 12/42 and 2/7

Grandpa ernie is shrinking! over the past 4 years his height decreased by a total of 2.4 cm. it decreased by the same amount each year. what was the change in grandpa ernie's height each year