Let:
T = Total money they have
Dc = Dog collar
x = Number of bags of food
Let's solve the inequality:
This means that they can buy 12 bags of food at most.
Since they plan to buy 2 bags of food:
This means they can do it and have $ 11.5 to spare
2 cm = 5 feet
1 cm = 2.5 feet
9 cm = 9 * 2.5 = 22.5 feet by
4 cm = 4 * 2.5 = 10.0 feet
477900 there you go use a calculator next time ;)