Answer:
First term a = 41
Step-by-step explanation:
Arithmetic Progression:
Common differences d = -2
[tex]S_{n}=\frac{n}{2}(2a+[n-1]d)\\\\S_{20}=\frac{20}{2}(2a+19*[-2])\\\\[/tex]
= 10*(2a - 38)
= 10*2a - 10*38
=20a - 380
[tex]S_{22}=\frac{22}{2}(2a+21*[-2])\\\\[/tex]
= 11 (2a -42)
=11*2a - 11*42
= 22a - 462
[tex]S_{22}=S_{20}\\\\[/tex]
22a - 462 = 20a - 380
22a = 20a - 380 + 462
22a = 20a + 82
22a - 20a = 82
2a = 82
a = 82/2
a = 41
First term a = 41
