The sum of third and ninth terms of arithmetic series is 20 and the difference between the twelfth and fourth term is 32.determine the value of the first term and the constant difference.

Answer 1

using the definitions:
a+2d + a+8d = 20
2a + 10d = 20
a + 5d = 10 **

a+11d - (a+3d) = 32
a+11d - a - 3d = 32
8d = 32
d = 4

sub into **
a + 20 = 10
a = -10

state your conclusion.