I think the text book answer is incorrect here, but wanted to have someone else confirm if this was the case. Thanks in advance.

Q.Find U_{n}, the n^{th}term of sequence: -5, 0, 5, 10,...

Attempt:U_{n }= a + (n - 1)d=> -5 + (n - 1)5 = -5 + 5n -5 = 5n - 10

Ans.: (From text book):U= 5n_{n }