Simplify each of the following expressions.

(a4)+(6a1)=\displaystyle {\left(-{a}-{4}\right)}+{\left({6}{a}-{1}\right)}=  

(a4)(6a1)=\displaystyle {\left(-{a}-{4}\right)}-{\left({6}{a}-{1}\right)}=  

(a4)(6a1)=\displaystyle {\left(-{a}-{4}\right)}{\left({6}{a}-{1}\right)}=