21 Divided by What Equals 51?
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 can we divide 21 by to equal 51?
Solving 21 Divided by What Equals 51
Here’s how you would set up this question as an equation:
21
x
=
51
\frac{21}{x} = 51
x 21 = 51
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, it can be done in two steps. The first step is to multiply both sides by x to isolate 21:
21
=
51
∗
x
21 = 51*x
21 = 51 ∗ x
Then we can isolate x on the right side of the equation by dividing both sides by 51:
21
51
=
x
\frac{21}{51} = x
51 21 = x
When we simplify the new equation, we can solve for x. In this example, we will round to the nearest three decimal places if that’s needed.
x
=
0.412
x = 0.412
x = 0.412
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!
What divided by 13 equals 18?
53 divided by what equals 6?
What is 6/1 divided by 74?
What is 2/10 divided by 17/12?
What is 36 divided by 20/14?