Can you please post the image.
If 30% were perfect, 70% were not perfect. So we know that 70% of the total number of photographs is 210.
p(70/100)=210 multiply both sides by 100
70p=21000 divide both sides by 70
p=300
So there are 300 photographs in all.
The slope form equation is: y=mx+b so once you plug in the numbers available through the diagram you get.
y=3x+4
