Question

What is the 19th term of the arithmetic sequence 15, 23, 31, ...?

Answer 1

y=mx+b
23=2m+b
15=m+b

When you solve for m and b
m=8
b=7

Now you have your equation
y=8x+7

You can plug in your input, which is 19
y=8*19+7
y=159

the answer will be 159

Answer 2

or just add 8 to the number...

Answer 3

It would kind of take a long time to add 8 to each number in the sequence up to the 19th term