What Divided by 21 Equals 39?
Methods
Setting up the problem:
In a problem like this, the “what” means that we’re working with a variable. The most common variable used in math is “x”. So, we could say what number, x, when divided by 21, equals 39?
Solving What Divided by 21 Equals 39
Here’s how you would set up this question as an equation:
x
21
=
39
\frac{x}{21} = 39
21 x = 39
The goal of the problem is to solve for x. To do this we need to change the equation so that x is alone on one side of the equation.In this case, we can do that by multiplying both sides of the equation by 21, resulting in this equation:
x
=
39
∗
21
x = 39*21
x = 39 ∗ 21
Then we simplify and find our answer:
x
=
819
x = 819
x = 819
So, the answer to the question “What divided by 21 equals 39?” is 819.To prove this, we can take the original problem:
x
21
=
39
\frac{x}{21} = 39
21 x = 39
And insert 819 in the place of x:
819
21
=
39
\frac{819}{21} = 39
21 819 = 39
Because this is true, the answer must be correct.
Practice Other Division Problems Like This One
If this problem was a little difficult or you want to practice your skills on another one, give it a go on any one of these too!
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9 divided by what equals 89?
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What is 15/4 divided by 7/18?
What is 31 divided by 3/17?