I have attached a diagram of the triangle described.
We can use any of the trigonometric functions to find angle x. Remember, SOH CAH TOA. And since we're finding the angle, we'll need to use an inverse trigonometric function. For this problem, I'll be using the sine function.
sin(x) = 84 / 85
x = sin^-1(84/85)
x = 81.2026 degrees (feel free to round to however many places you need)
Hope this helps!! :)
