Question: 
Write a function to find t-nth term of arithemetic progression.


Model's Code:
def tn_ap(a, d, n):
    return a + (n - 1) * d



Sample Correct Code:
def tn_ap(a,n,d):
  tn = a + (n - 1) * d
  return tn


Asserts:
assert tn_ap(1,5,2)==9
assert tn_ap(2,6,4)==22
assert tn_ap(1,4,5)==16


Tests:
Test 1 of 3: FAIL: AssertionError()

Test 354 of 974: 256/354 (72.31638418079096%): failed