78 Divided by What 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 can we divide 78 by to equal 21?
Solving 78 Divided by What Equals 21
Here’s how you would set up this question as an equation:
78
x
=
21
\frac{78}{x} = 21
x 78 = 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, it can be done in two steps. The first step is to multiply both sides by x to isolate 78:
78
=
21
∗
x
78 = 21*x
78 = 21 ∗ x
Then we can isolate x on the right side of the equation by dividing both sides by 21:
78
21
=
x
\frac{78}{21} = x
21 78 = 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
=
3.714
x = 3.714
x = 3.714
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 63 equals 59?
77 divided by what equals 36?
What is 2/1 divided by 35?
What is 12/14 divided by 19/5?
What is 61 divided by 10/18?