About the Equation

This time, let talking about the equation. In general, the equation can be written in the following equation.

A + B = C + D

Let us think like a pair of scales that be used to measure the weight.
If the weight of the left and right are the same, a pair of scales will maintain the parallel. And if not same, it will be inclined to the heavy side.
Equation is only to write by formula that state maintained the parallel.
Let write by numeral formula that above.

3 + 1 = 2 + 2

The value of the left and right are the same. So, a pair of scale is the balance is to remain parallel.
When maintain the parallel(value of the left and right are equal), does not change even if divide the same numeral to the left and right. Subtraction, addition, multiplication is same too(The value of the left and right is always the same).

We can then use such a property, will find a number that we do not know. And We called it, 'The equation'.
Suppose a number 'H' that we do not know.

4 - H = 30

Let look for the value of H by solving the above equation.

Case of The equation, is same that subtract same number in the left and right.
So, can be solved as follows.

4 - 4 - H = 30 - 4

H = 26

The value of H is 26. Obvious, is not it? Let's think a little more easily this.
If you move number to the right on the left, change the sign.

4 - H = 30

H = 30 - 4

H = 26

Like this. 
If you don't know two or more of the following?

(100 X A) + (50 X B) = 300 

Like this, on the expression representing the multiplication of numbers and letters, you can omit the multiplication sign. 

100A +50 B = 300 

Thus.

If this is the case, you can answer a variety of.

A = 0, B = 6 

A = 3, B = 0 

A = 2, B = 2 

It is All right answer. 

Also, even if put any number, there is also a case where it is always correct equation. 

4A = A + A + A + A 

5 (A + B) = 5A +5 B 

On the Expression of the above, Even if put any number, there is same always left and right. We called it 'Identical equation'