That's one hefty problem!
First lets pull that 3 out of there since it is a factor of 3, 24, and 28.
Now we have 3(16a5b2 - 8a4b3 + a3b4)
Now lets look at A. a3 is the smallest A we have so lets pull that out too!
Now we have 3a3(16a2b2 - 8ab3 + b4)
Were getting close! There's only one more variable left that looks like it repeats and that's B! Looks like b2 can be pulled out as well so lets do that!
Now we have 3a3b2(16a2-8ab + b2)
It almost looks like were done considering we've factored out a 3, an a3, and a b2 but there's one more thing we can do. notice that what's inside the parenthesis is a quadratic. That means there's a chance that we can factor that too!
Lets do it.
(4a - b)(4a - b)
Lets double check to make sure it works. To do that we foil it.
4a * 4a= 16a2
4a * -b= -4ab
-b * 4a= -4ab
-b * -b= b2
adding those up we get 16a2-8ab+b2
Looks like it worked so were finally done!
Our answer is
Best of Luck!