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March 6, 2015

March 6, 2015

Posted by **Da S** on Thursday, February 2, 2012 at 9:00am.

He added 20 red pens into the box and the ratio became 2:1.

a. were there more red pens or blue pens in the box at the end?

b. how many red pens were there in the end?

c. how many blue pens were there?

- math,(fraction) -
**Steve**, Thursday, February 2, 2012 at 10:50amwell, since the ratio r:b = 2:1 I'd say there were more r's...

(r+20)/b = 2/1

r/b = 3/4

so, b = 4/3 r

(r+20)/(4/3 r) = 2

r+20 = 8/3 r

5/3 r = 20

r = 12

so, there were 32 reds at the end

there were 4/3*12 = 16 blue pens. Note that 16 = 32/2 as well.

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