The Question:

BLYs Method

HSAs Method

SMAs Method

Would have done it similarly but without introducing the variable B, so all in terms of R

R : 4R

R+7 : 3(R+7)

We know the Bs were unchanged so

4R = 3(R+7)

Giving us R=21

And then B is 3(21+7)=84

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*Related*

I like SMA’s approach of focusing on the unchanged and leaving in terms of r; although I’d use x to represent number of beads (any colour) since I’m predicting that pupils will be confused with blue beads represented with r.

HSA’s approach is really neat and demonstrates some pretty smooth thinking. 💭 BLY

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