Let

$\{\begin{array}{c}\text{:}{\displaystyle \underset{0}{\overset{2}{}}}f(x)dx=-10\\ {\displaystyle \underset{0}{\overset{3}{}}}f(x)dx\end{array}$

Use these values to evaluate the given definite integrals.

a$.{\displaystyle \underset{0}{\overset{2}{}}}(f(x)+g(x))dx=$

b$.{\displaystyle \underset{0}{\overset{3}{}}}(f(x)-g(x))dx=$

c$.{\displaystyle \underset{2}{\overset{3}{}}}(3f(x)+2g(x))dx=$

d$.$ Find the value a such that

$a=,{\displaystyle \underset{0}{\overset{3}{}}}(af(x)+g(x))dx=0.$