Is One Less Than Three Times A Number Equal To The Same Number Plus 19?

An equation can be written for your number (n) as follows.  3n - 1 = n + 19  2n - 1 = 19    (subtract n from both sides)  2n = 20    (add 1 to both sides)  n = 10    (divide both sides by 2)

The number is 10.

Check  3*10 - 1 = 29 = 10 + 19