What is the 19th term in sequence - 1,-5,-9, ...

The sequence starts at - 1 and counts backwards by 4s, so we can find the nth number in the sequence by evaluating the expression - 1 - 4n for any number n. Here, we want to find the 19th term, so we set n = 19 and find it to be - 1 - 4 (19) = - 1 - 76 = - 77

This is so easy, the answer is - 85