We have a random triangle with base x, and height x - 5. Remember, the area of a triangle is base*height / 2, in this case base*height = 84.

Plugging in the values, we have (x)(x - 5) = 84. Opening parenthesis we have \(x^2 - 5x = 84\). Factoring we have (x - 12)(x + 7) = 0

Taking the positive value of x from -7 and 12, we have x = 12. Meaning that the height is 7.

**Thus, the base = 12 units, the height = 7 units**.