Lesson: Finding x Percent of y

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Sir, the way you teach and your explanation are so clear and interesting that makes math fun for non math student like me.Kudos to you and your teaching.

HI BRENT,can u pls explain this problem
If a ticket increased in price by 20%, and then increased again by 5%, by what
percent did the ticket price increase in total?

gmat-admin's picture

Sure thing!

Let's say the ORIGINAL ticket price is $100

After a 20% increase, the new ticket price is $120 ($100 + 20% of $100 = $100 + $20 = $120)

After a 5% increase, the FINAL ticket price is $126 ($120 + 5% of $120 = $120 + $6 = $126)

If the ORIGINAL price was $100 and the FINAL price is $126, then the price increase is 26%

After solving some question I feel like always x or whole comes after of . So it okay presume the same .
gmat-admin's picture

I'm leery about saying "always," but I can't think of an example where the "whole" does not come after the word "of"

If course there are questions like "What is 10% of 40% of 60?" but after we calculate 40% of 60, we basically treat it like a new "whole."

If the total payroll expense of a certain business in year Y was $84,000, which was 20 percent more than in year X, what was the total payroll expense in year X ?

(A) $70,000

(B) $68,320

(C) $64,000

(D) $60,000

(E) $52,320
It's a easy question but I don't know what I doing . I used x /84000= 20/100 . What method should I use
gmat-admin's picture

If K is 20% more than W, we can write: K = 1.20W

So, with this question, we're told that year Y's payroll expenses (of $84,000) is 20% more than in year X's expenses.

So, we can write: (year Y's payroll expenses) = 1.20(year X's payroll expenses)

In other words, $84,000 = 1.20(year X's payroll expenses)

Divide both sides by 1.20 to get: $84,000/1.20 = year X's payroll expenses

Evaluate: $84,000 = year X's payroll expenses

Answer: A

In a certain furniture store, each week Nancy earns a salary of $240 plus 5% of the amount of her total sales that exceeds $800 for the week. If Nancy earned a total of $450 one week, what were her total sales that week ?

A. $2,200
B. $3,450
C. $4,200
D. $4,250
E. $5,000
I used eliminating method I choose 5000-800. 4200 *5/100 for 210 then 450-240 gives 210 . This tell us it was right . How will I use your method in this
gmat-admin's picture

Let x = total sales

Nancy gets 5% commission on sales that exceed $800

So, commission = 5% of (x - 800)

This means TOTAL SALARY = $240 + 0.05(x - 800)

We get: $450 = $240 + 0.05(x - 800)

Subtract 240 from both sides: 210 = 0.05(x - 800)

Divide both sides by 0.05 to get: 4200 = x - 800

So, x = 5000

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