ANSWER
y=7
EXPLANATION
The horizontal asymptote of an exponential function

is y=c.
The given exponential function is

When we compare to

c=7, therefore the horizontal asymptote is y=7.
The ilne paralell to x=something is x=something else (both are constants)
slope=rise/run
x=-3
it rises infiniley and runs 0 (goes left to right 0)
slope=infinity/0=undefined
the slope is undefined
paralell lines have same slope
so the slope of a paralell line is also undefined
15.5 x 12.4 = 192.2 so the answer is 192.2 square feet.