53. Properties of integrals Suppose \( \int_{0}^{3} f(x) d x=2 \), \( \int_{3}^{6} f(x) d x=-5 \), and \( \int_{3}^{6} g(x) d x=1 \). Evaluate the following integrals.
a. \( \int_{0}^{3} 5 f(x) d x \)
b. \( \int_{3}^{6}(-3 g(x)) d x \)
c. \( \int_{3}^{6}(3 f(x)-g(x)) d x \)
d. \( \int_{6}^{3}(f(x)+2 g(x)) d x \)