First, separate the expression into two parts, make sure each part has two terms with similar components. For each part, take out the number or variable that is in both numbers.
(u + ux) + (4t + 4tx) Now, factor the u out of the first set
u(1 + x) + (4t + 4tx) Factor the 4t out of the second set.
u(1 + x) + 4t(1 + x) Combine the two outside terms into one set of parentheses and take away one of the (1 + x)'s because you don't need two.
(u + 4t) (1 + x)