[tex]\huge \boxed{4a+20}[/tex]
We can do this using the distributive property, which states that [tex]a(b+c)=ab+ac[/tex].
Distribute the [tex]4[/tex] to the [tex]a[/tex] and the [tex]5[/tex]. [tex]4a+4(5)[/tex]
Multiply. [tex]\displaystyle \boxed{4a+20}[/tex]