Write a function to find t-nth term of arithemetic progression.
def tn_ap(a,n,d):
  tn = a + (n - 1) * d
  return tn
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to find t-nth term of arithemetic progression.
def tn_ap(a,n,d):
  tn = a + (n - 1) * d
  return tn[/INST]assert tn_ap(1,5,2)==9
assert tn_ap(2,6,4)==22
assert tn_ap(1,4,5)==16</s>