What Divided by 90 Equals 21?
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 90, equals 21?
Solving What Divided by 90 Equals 21
Here’s how you would set up this question as an equation:
x
90
=
21
\frac{x}{90} = 21
90 x = 21
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 90, resulting in this equation:
x
=
21
∗
90
x = 21*90
x = 21 ∗ 90
Then we simplify and find our answer:
x
=
1890
x = 1890
x = 1890
So, the answer to the question “What divided by 90 equals 21?” is 1890.To prove this, we can take the original problem:
x
90
=
21
\frac{x}{90} = 21
90 x = 21
And insert 1890 in the place of x:
1890
90
=
21
\frac{1890}{90} = 21
90 1890 = 21
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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91 divided by what equals 96?
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What is 46 divided by 1/10?