Use geometry to evaluate (see attached) (calculus) the integral from 0 to 6 of the function f of x, dx for f of x equals 3 for x less than or equal to 3 and equals the quantity 6 minus x for x greater than 3. 27 13.5 12 10.5

check the picture below.

notice the area is just a 3x3 square and a triangle with a base of 3 and a height of 3, simply get the area of both, add them up, and that's the area of the piece-wise on that range.