The y values are not changing so y = 6 describes the line
A15=243
74-61=13
87-61=13
So they're adding 13 every time.
A15 is 11 terms from A4 which is the last one you are given so 11*13=143
143+100=243
4000+7000= 11,000 nearest thousands
4281+7028= 11,309 actual number
15*19=285
base times height is the formula