well we have to look at.what f (4) means.
if i say,f (x) = x and then i say fund f (4), then all i do is substitute 4 for every x. so
f (4) = 4.
if i had said f (x) = x + x, then
f (4) = 4 + 4
so we have f (x) = e^(x-3). so
f (4) = e^(4-3)
f (4) = e^(1)
anything raised to the first power stays the same so
f (4) = e
ae know e = 2.718. so
f (4) = 2.718
