6th Grade Math Textbook, Fundamentals

Lesson 7-9 for exercise sets. &KDSWHU 

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Find the percent decrease.

1.from $5 to $4 2.from 0.7 to 0.07 3.from 90.6 to 35.2

Find the loss to the nearest cent.

4.Cost: $385.20 5.Cost: $79.25

Percent loss: 3.5% Percent loss: 3.4%

6.Discuss and Write How is finding the percent decrease like finding

the percent increase? How is it different?

Merchants sometimes suffer a losson the sale of items.

When there is a loss of money, the item is sold belowits cost.

Finding the amount of loss is similar to finding the amount of profit:

Multiply the original cost by the percent loss.

A nursery bought spruce trees for $80 each. After the holidays, the

nursery sold the trees that were left at a loss of 20%. What was the

loss (L) per tree on the trees sold after the holidays?

Method 1 Write an Equation

Let Lthe amount of loss.

L20% • $80

L0.20• $80

L$16.00

Method 2 Write and Solve a Proportion





100 L80 • 20

 Divide both sides by 100.

L 16

160 0

100

100 L

100

Substitute 80 for the cost (C)

and 20 for the percent loss.

Cross multiply.

20

100

L

80

percent loss (%)

100

loss (L)

cost (C)

Multiply the original cost, $80,

by the percent loss, 20%.

Write 20% as a decimal,

then multiply.

So the loss on each tree was $16.

When an item is sold at a loss, the selling price

is lessthan the cost. Subtract the loss from the

cost to find the selling price.

A family bought a car for $21,000 and then

sold it at a loss of 30%. Find the selling price.

SP$21,000 (30% of $21,000)

SP$21,000 (0.3• $21,000)

SP$21,000 $6300

SP$14,700

So the selling price is $14,700.

The amount of loss is $6300, so subtract

$6300 from the cost, $21,000.

Write 30% as the decimal 0.3,

and multiply 21,000 by 0.3.

The cost is $21,000, and the

loss is 30% of $21,000.

$0 $21,000

% loss

loss selling price

cost

0% 100%