3/5 of **what number** = 15?

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Think about what you know.

First, you are dealing with fractions, which means that each part has to be equal.

Second, you know that if you add 3 of those equal parts together you get 15.

The next step is to figure out what one of those parts would be. If you divide 15 by 3, that gives you the answer to this step.

15/3 = 5

We know from the problem that each of the equal parts is 1/5 of the target number. Since we know that each part = 5, then the number has to be:

5 x 5 = 25

*****

The way you would write the problem out mathematically is:

3 15

__ = __

5 ?

There are two ways to solve it from here. **One** is that you know you have to multiply 3 by 5 to get to 15, so do the same in the denominator.

3 x 5 15

__ = __

5 x 5 25

**The other **way to solve it (which you need to use if you can't figure out what to multiply by) is cross-multiplication.

3 15

__ = __

5 ?

3 x ? = 5 x 15

3 x ? = 75

? = 75/3 = 25

If 3/5 is 15, then 1/5 must be 5 (15/3).

So 5/5 of that number would be 5 x 5 = 25.

So 25 is your answer.

In word problems, "of" means multiply, "what number" means "x," and "is" means "=," so in math language, "3/5 of what number is 15" turns into: 3/5(x)=15. Then just solve for x (invert and multiply).

x=15(5/3)

=75/3

=25.

(3/5)n=15 Let n equal the missing number

you first multiply by 5 to both sides so it will cancelled out in the left and multiply 15*5 = 75

3n=15*5

3n=75

Then you divide both sides by 3 so it will cancelled out in the left and leave n by itself and then just divide 75/3 = 25

so n=25

This is quite simple "zero0master". All you have to do is to invert 3/5 which becomes 5/3 and multiply by 15. Your answer should be 25

let the number be x

(3/5)x = 15

therefore x = 15 * 5/3

= 25

Let that number be x, so the problem would look like that below:

3/5*x=15

3x/5=15

3x=15*5

3x=75

x=25 (the number). This question above is a algebraic problem.

**let the number be X**

*hence 3/5*x = 15*

* x = 15*5/3*

* x = 25*

3/5x=15

5/3*3/5x=15*5/3

x=25

3/5= 15, which equals 60% of x.

We can multiply 15 by 5/3 in order to get our answer.

When we do this, we end up with 25.

5/3x15=25

(3/5)x=15

(to get the x alone, divide 3/5 by both sides)

x = 15/(3/5)

x= 25

3/5 of some number equals 15. Recalling that of means multiply, we can rewrite this algebraically as:

(3/5)x = 15

Now its a matter of isolating x. Divide both sides by 3/5

15/(3/5) = 25

25. Try working backwards.

3/5 of **what number** = 15

`15x5= 75 `

75/3 = 25

so 15 is `3/5` of 25

to check

25x3=75

`75/5 = 15`

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