We have
[tex]\displaystyle \int_0^5 g(x)\; dx = \int_0^5 (f(x)-3)\; dx = \int_0^5 f(x)\; dx - \int_0^5 3\; dx[/tex]
The first integral is known and it is 48.787. The second integral is the area of a rectangle:
[tex]\int_0^5 f(x)\; dx - \int_0^5 3\; dx = 48.787 - 15 = 33.787[/tex]