To solve, you need to find the surface area of the box. Since it is a rectangular prism, we know it has 6 sides. The top and bottom will be the same area, the two long sides will be the same, and the two small sides will be the same. So we find the area of one each of the top, long side, and small side then add them together and then multiply by two (to account for the other sides).
Top
A = L x W
A = 9 in x 7 in = 63 in^2
Long side
A = L x W
A = 9 in x 5 in = 45 in^2
Short side
A = L x W
A = 7 in x 5 in = 35 in^2
Add them together...
63 + 45 + 35 = 143 in^2 (that is the area of 3 sides so now we multiply by 2)
143 in^2 x 2 = 286 in^2
She needs
D. 286 in^2 of wrapping paper