The rule is to subtract 4. We know that the tenth term is 18. Let’s go back 10 terms, so we can find the 0th term. 4*40 is 40, and 18 + 40 = 58. Next, we need to find the 4th term of this sequence. We can do that by multiplying 4 by 4, which is 16. Next, we subtract 58 from 16. This gives us 42.
The fourth term is 42.
An equation to represent this situation is 58 - 4n. We can plug in 10 to check our answer. 58 - 4(10) is 58 - 40 which is 18.