What Divided by 21 Equals 78?
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 78?
Solving What Divided by 21 Equals 78
Here’s how you would set up this question as an equation:
x
21
=
78
\frac{x}{21} = 78
21 x = 78
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
=
78
∗
21
x = 78*21
x = 78 ∗ 21
Then we simplify and find our answer:
x
=
1638
x = 1638
x = 1638
So, the answer to the question “What divided by 21 equals 78?” is 1638.To prove this, we can take the original problem:
x
21
=
78
\frac{x}{21} = 78
21 x = 78
And insert 1638 in the place of x:
1638
21
=
78
\frac{1638}{21} = 78
21 1638 = 78
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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26 divided by what equals 80?
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