Bobby draws artwork measuring 2.25 inches by 2 inches. He makes a copy of the artwork, enlarging it so that it's dimensions are now 3.15 inches by 2.8 inches. What scale factor did he use to create the copy of the original artwork? Write your answer as a decimal.
To find the scale factor, we can divide the dimensions of the copy by the dimensions of the original artwork.
So, the scale factor is $\frac{3.15\text{ inches}}{2.25\text{ inches}} = \boxed{1.4}$ or $\frac{2.8\text{ inches}}{2\text{ inches}} =1.4$.