Let x be the base of the triangle, and
2x + 4 be the height.
One of the ways in solving for the area of a triangle is to half the product of its height (h) and base (b). Mathematically,
A = bh / 2
Substituting the expression for b and h and the given condition for the area,
(x)(2x + 4) / 2 ≤ 168