If your question is, "how much had Mr. Kork paid for the car?"
(8,400-200)/.4=$20,500
0.45 * 2 is 0.9
$1.44 * 2 is $2.88
$1.44/9 is $0.16
$0.16 * 2 is $0.32
$2.88+$0.32 is $3.20
The answer is $3.20
First term, a
1
=4
Second term, a
2
=8
Common difference, d=a
2
=a
1
d=8−4=4
∴ The common difference is 4
The answer is −3.555555555555556 but you can just put -3.55