# 1)tickets decreased from \$90.00 to \$85.002)a \$170.00 bicycle decreased to \$155.00there are 2 questions.please help me find the percent of decrease for each of the following items.

cburr | Middle School Teacher | (Level 2) Associate Educator

Posted on

This might be an easier way to think about it.

In the first problem, the amount of decrease is \$5.  What you need to find is what percent \$5 is of \$90 (since \$90 is the number you started with).

Percent problems can always be solved using:

Part / Whole = %

Just plug in what you know and solve it to find the missing piece.  Here, you know the part (\$5) and the whole (\$90).

So, the % = \$5 / \$90 = .0555555 etc

Remember that .05 is the same as 5%.  So, just round the answer to however many places your teacher wants.

.0555555 etc = .0556 (5.56%) or .056 (5.6%) or .06 (6%) depending on how exact you need to be.

Posted on

Both of these are simple percentage problems. Your percentage formula is, as always:

p/w=%/100

where the part of the whole is equal to the percentage over 100.

So in this case, your part for number 1 is \$5 (the amount decreased) and your whole is \$90. Your percentage is unknown, so let's call that X. So your re-written formula should be:

\$5/\$90 = X/100

This is a proportion, so we can cross-multiply, so:

\$5 x 100 = 500

\$90 x X = 90X

So now we have 90X = 500.

In order to isolate X, we need to divide 90 from both sides.

90X / 90 = X

500 / 90 =  5.56

So, X = 5.56, and therefore the price decreased by 5.56%.

For number 2, your part is \$15, your whole is \$170, and again your percentage is unknown, X.

\$15/\$170 = X/100

So again, we cross-multiply, and get:

\$15 x 100 = 1500

\$170 x X = 170X

And therefore,

1500 = 170X

Now we isolate X by dividing out the coefficient from both sides.

170X / 170 = X

1500 / 170 = 8.82

Therefore, X = 8.82%, your percentage of decrease.

givingiswinning | Student, Grade 10 | (Level 1) Valedictorian

Posted on

1.

90-85=5

5/90 x 100 = 5.55%

2.

170 - 155 = 15

15/170 x 100= 8.82%

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

Posted on

1)tickets decreased from \$90.00 to \$85.00

90-85=5

5/90 x 100 = 5.55%

2)a \$170.00 bicycle decreased to \$155.00

170 - 155 = 15

15/170 x 100= 8.82%

revolution | College Teacher | (Level 1) Valedictorian

Posted on

1) The tickets decreashed from 90 dollars to 85 dollars, so the price change is 5 dollars.

Percentage decrease= decrease/ original amount * 100% so:

% decrease= 5/90 * 100%= 5.55%

2) The price change is 170-155= 15 dollars

% decrease= 15/170*100%= 8.82%