ANSWER
The correct answer is [tex]296[/tex] square inch.
EXPLANATION
We just have to find the total surface area.
That is we find the area of the two triangular faces and add it to the area of the three rectangular faces.
Recall that:
[tex]Area\: of\:Triangle =\frac{1}{2}\times base \times height[/tex]
and
[tex]Area\: of\:Rectangle =length \times width[/tex]
[tex]Total\:Surface\:Area=\frac{1}{2} \times 8\times 7 \times 2+ 10\times 8 \times 3[/tex]
[tex]Total\:Surface\:Area=4\times 7 \times 2+ 10\times 8 \times 3[/tex]
[tex]Total\:Surface\:Area=56+ 240[/tex]
[tex]Total\:Surface\:Area=296[/tex] square inches
Hence Nikki used 296 square inches of cloth to make the tent.