# How do you factor 35ab + 56a + 10kb +16k?

$35 a b + 56 a + 10 k b + 16 k = \left(7 a + 2 k\right) \left(5 b + 8\right)$
First we note that we can take out $a$ and $k$ at the left and right terms of the polynomial respectively
$35 a b + 56 a + 10 k b + 16 k = a \left(35 b + 56\right) + k \left(10 b + 16\right)$
$a \left(35 b + 56\right) + k \left(10 b + 16\right) = 7 a \left(5 b + 8\right) + 2 k \left(5 b + 8\right) = \left(7 a + 2 k\right) \left(5 b + 8\right)$