Question 849932
153 = ½(2a + d(n-1))n
9= a + 2d
Some possible answers
a = 1,   d = 4,   n = 9
a = 99,   d = -45,   n = 2
a = 93,   d = -42,   n = 3
a = -57,   d = 33,   n = 6