six less than four times a number is fifteen find the number

Question

Do any one know how to this problem?

Answer 1

Since we are not yet sure what our number is, we should use a variable to represent that number, and then solve for that variable. 

 

I will use "x" as our variable to represent the number we are trying to find. 

 

Let's take the problem piece by piece.

 

Six less than four times a number.

 

If we are using x to represent our number, we know that when we do four times that number we are multiplying x times 4, which is the same as writing "4x."

 

Next we know that we are taking six less than 4x. Six less than means we will be subtracting 6 from our 4x, which is the same as writing 4x - 6.

 

Finally, we know that six less than 4x (4x - 6) equals 15. Now we have a full equation:

 

4x - 6 =15

 

Now we have to solve for x by getting x by itself:

 

4x - 6 = 15

add 6 to both sides to move the 6 away from the x

4x = 21

now divide by 4 to get x by itself

x = 21/4, in decimal form this is 5.25