Question

I think of a number, multiply it by 3 and subtract 1

Answer 1

The formula for that statement is:

Let, n = number

" 3n-1 " - there are no brackets needed because of PEDMAS

Answer 2

If you want to know the formula ..
You just basically think of your number as 'y' where y could be any number you want. multiplying it by 3 means

3*y or 3y

then substract 1 so
(3y) -1

OR 3y-1

Hope this answers your question!