A sign at a recycling center states that 118 pounds of recycled newspapers saves one tree. How many pounds of newspapers will save 3 trees?

1 Answer
Jade
Nov 20, 2016

354 pounds

Explanation:

To solve this word problem, set up a proportion. A proportion is a fraction set equal to another fraction.

#"lbs of recycled newspaper"/"number of trees saved"#

Using the above fraction, set up one of the two fractions

lbs of recycled newspaper: 118

Number of trees saved: 1

#(118lbs)/(1 tree)#

Remember, a proportion is made up of two fractions. So, using the original equation, set up another fraction

lbs of recycled newspaper: ?

Since we are trying to find the lbs of newspaper, that is going to be labeled as variable #x#

lbs of newspaper: #x#

Number of trees saved: 3

#x/ (3 trees#

Now that there are two fractions, we can set up a proportion by setting the two fractions equal to each other

#(118lbs)/(1 tree)=(x)/(3#

To solve a proportion, cross multiply:

#118xx3=354#

#1xxx=x#

Keep in mind that the product of the two cross multiplications are still set equal to each other

#x=354#

Now, if you revisit what we set #x# equal to, #x# equals the pounds of newspaper recycled that saved 3 trees.

So, 354 pounds of newspaper saves 3 trees.

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