Answer:
719.412
Explanation:
S(x)=-.228x^2+8.154x-8.3 x=7 feet
Plug in 7 for x, you'll convert to inches at the end
S(x)=.228(7^2) +8.154(7)-8.3
S=49(.228)+8.154(7)-8.3
S=11.173+57.078-8.3
S=59.951
Multiply by 12 to get inches
719.412
(If this answer doesn't work then you probably need to convert to inches before plugging in for x. 7 x 12=84 so plug that in.)