Sadies sand Cost=5T +200
Gregs sand pit cost= 12T+50
Sadie sand Gregs sand pit
C=5T+200 c=12T+50
C=5 (0)+200 c=12 (0) +50
C=200 c=50
(0,200) (0,50)
The rest are done the same by substituting T with the increments of 10 like the x-axis. I started the first point at x=0.