Three numbers are known to be equal difference sequence, and their sum is 12 and product is 60

Three numbers are known to be equal difference sequence, and their sum is 12 and product is 60

Let the middle number be a, then the first number be A-D, the third number be a + D, a + (A-D) + (a + D) = 12, and a = 4
A (A-D) (a + D) = 60, D1 = 1, D2 = - 1, when d = 1, a + D = 5, A-D = 3, when d = - 1, a + D = 3, A-D = 5
To sum up, the three numbers are 3, 4 and 5 respectively