Chapter 4 Quadratic Functions and Factoring - 4.4 Solve ax(squared) + bx + c = 0 by Factoring - 4.4 Exercises - Skill Practice - Page 264: 52

$x=5$.

We know that the area of the triangle is half the product of the base and its according height. Hence here: $(5x-2)(2x)\cdot0.5=115\\5x^2-2x-115=0\\(5 x + 23) (x - 5)=0$ Thus $x=5$ or $x=-4.6$ but $x$ has to positive, thus $x=5$.