Use distributive property:
a(b + c) = ab + ac
and [tex]a^n\cdot a^m=a^{n+m}[/tex]
[tex]2ab(xa^6+ya^4+7)=(2ab)(xa^6)+(2ab)(ya^4)+(2ab)(7)\\\\=2a^{1+6}bx+2a^{1+4}by+(2)(7)ab\\\\=\boxed{2a^7bx+2a^5by+14ab}[/tex]
ok I couldnt tell if the 4+7 was an exponnenet or not so i just did it both ways for you:
if only 4 is an exponent : 2a^7 bx + 2a^5 by +14ab
if '4+7' is an exponent: 2a^12 by+2a^7bx
