We know how wide the billboard will be. Therefore, to know how much the original image should be enlarged, you have to divide the final width of the billboard between the current width of the invoice.
[tex]\frac{48 feet }{6.14 inches} =7.81\frac{feet}{inches}[/tex]
Therefore the correct answer is option D.
In order for the bill to cover the billboard, the bill must be expanded by a factor of 7.81 feet in length by inch in length.