Mr. Owens has 20 five- and ten- dollar bills that have a total value of $165. How many five- dollar bills does he have?

Question

Solve the problem using an equation .

Answer 1

First you want to establish unknowns. The most simple way to start is to let x be what you are looking for. We will let x be the number of 5 dollar bills Mr. Owen has. Since Mr.Owens has a total of 20 bills, we can use this information to express the amount of 10 dollar bills in terms of x as well. Therefore, 20-x will represent the number of 10 dollars bills Mr. Owens has. Now let's create an equation base on the information given.

If you want to know the value of the money you have, you multiply the number of bills by the value of that bill, so let's do that with the specific information we have.

5(x) +10(20-x)=165

Now let's do the Math!

5x+200-10x=165 (Combine Like terms first)

200-5x=165

+5x +5x (Isolate the variable. When possible keep it positive and on the right side)

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200=165+5x

-165 -165 (Continue until the "x" term is on one side alone and all other terms on other side)

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35=5x (Divide both sides by 5 to get x by itself)

35/5=5x/5

7=x

7=the number 5 dollar bills Mr. Owens has