Answer:
See below.
Step-by-step explanation:
If the triangle is right-angled then x = 12 and x + 4 = 16, because 20^2 = 12^2 + 16^2.
In an acute triangle if c is the hypotenuse then c^2 < a^2 + b^2 so x must be greater than 12. Also as 20 is the longest side x cannot be 16 or greater.
So pick a value greater than 12 and less than 16.
