Determine the 20th term of the sequence 1,4,7, ...

Each term goes up by 3 so if n is the nth term and y is the value y=3n but the first term is 1 not 3 so

y=3n-2

The 20th term is n=20 so

y = 58

It is 58

That's the 20th number in the sequence since each term is 3 more than the last number. An easy way to do this is multiply 19 times 3 because there are 19 terms after one. Then multiply by 3 because each term is 3 more than the last term. After you do 19 x 3 you get 57 right? Then add 57 to 1, the first term, to get 58.