Algebra

# Equations Warmup

Five years ago I was $\frac{1}{3}$ as old as my oldest sister, but now I'm half her age. How old am I?

How much does a red square weigh?

What is the weight, in grams, of one light-pink gem?

Hint: this problem can be solved efficiently using algebra, or creatively, by visualizing the gems and weights moving around until there are only grams on one side of your scale and pink gems on the other. (Check out the staff solution to see how to solve this problem both ways.)

Five cows produce 5 gallons of milk in 5 days.

If every cow produces milk at the same rate, how many days will it take 3 cows to produce 3 gallons of milk?

A pencil and notebook together cost one dollar (100 cents). The notebook costs 90 cents more than the pencil.

How much does the pencil cost?

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