The basic method is to remove brackets, move items, and combine the coefficients of similar items into one.

Delete brackets: 6x-2 = 40

Transposition: 6X=40+2

Merge similar projects: 6X=42

The coefficient becomes one: X=7.

Solving a linear equation is the basis of solving a higher-order equation, and every step should be based on theorems and axioms. If there is no basis, it is nonsense. If you are familiar with it, you can omit the process! But I don't advocate saving, even for college entrance examination students. Of course, it is not necessary to write it all on the answer sheet. Be sure to put it on the draft, even if it's as simple as 1+ 1=2, because it's convenient for you to check, and you don't have to calculate it again when you check, which saves time and is not easy to make mistakes!

2. It is known that s =18.2cm2 a = 5.2cm..

Question: H.

Solution: For S=ah/2, H = 2s/a =18.5x2/5.2 = 37/5.2 = 7 (cm).