Question

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?

Answer 1

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.