"A drawer has some red, green, and blue marbles. There are 33 marbles.
There are 4 times as many red marbles as green marbles. There are half
as many blue marbles as green marbles. How many blue marbles are in
the drawer?"

Can someone plz show me the way to solve this using units and division? This question was in the 4th grade Benchmark Assessments, part of the Math in Focus (Singapore Math) curriculum.

r=red
blue=b
g=green

r+g+b=33
r=4g
b=g/2

we must convert to a common unit which could be the smallest unit so we must convert to blue

b=g/2 or g=2b
r=4g
r=4(2b)
r=8b

r=8b
g=2b
b=b

r+g+b=33=8b+2b+b=11b
11b=33
divide both sides by 11
b=3

g=2b
g=2(3)
g=6

r=8b
r=8(3)
r=24

r=24
g=6
b=3

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