It is generally inconvenient to replace the original formula with the original formula when copying. Usually it is a polynomial or used for factorization.

S8-S3 = A4+A5+A6+A7+A8 = 5A6 =10, so S1= A1+A2+A3+…+A1.

A formula (non-equality and inequality) that needs to be solved can generally be omitted as the original formula = because the original formula is longer. That is to say, the original formula does not include equal sign or greater than sign, less than sign, unequal sign and these symbols, but only includes operations such as addition, subtraction, multiplication and division, brackets and mathematical symbols such as fox, mystery, angle and square.

Form:

Connect equal formulas (or numbers expressed in letters) with "=".

Equations are divided into equations with unknowns and equations without unknowns.

For example:

X+1= 3-an equation with unknowns;

2+1= 3-an equation without unknowns.

It should be noted that some equations with unknowns have no solutions, but they still have no solutions, such as x+1= x-x.