Wendy, Yvonne, and Elizabeth are baking cookies for a bake sale. Wendy

R=w/t
1/10=W
1/6=y
1/15=E

(W+E =2 hours)

1/10+1/15=1/2
5/30=x/2
1/3 (work done by W and E )

Remaining work

1- 1/3 = 2/3

R=w/t

1/6=2/3÷x

X= 4

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I hate fractional jobs. Let's just make up a number of cookies. 60 looks like it'll work well.
Wendy can bake 60 cookies in 10 hours, so she bakes 6/hour.
Yvonne can bake 30 cookies in 3 hours, so she bakes 10/hour.
Elizabeth can back 20 cookies in 5 hours, so she bakes 4/hour.
Together, they bake 20/hour, so in 2 hours, they bake 40.
That leaves 20 for Yvonne to bake on her own. At a rate of 10/hour, it'll take 2 hours.

Answer choice B.


There's no variable in the question, but the instinct is to make up a variable out of thin air. Why would we work with X? If we are going to make something up, let's at least make it the easiest thing to work with. We are plugging in for a hidden variable.

ThatDudeKnowsHiddenPlugIn