Answer:
x = 4
Step-by-step explanation:
We can use cross products to solve
84/12 = 28/x
84 * x = 12 *28
Divide each side by 84
84x/84 = 12*28/84
x =4
Answer:
-3/4
Step-by-step explanation:
For any equation,

assume solution of a form, 
Which leads to,

Simplify to,

Then find solutions,

For non repeated real root y, we have a form of,

Following up,
For two non repeated complex roots
where,

and,
the general solution has a form of,

Or in this case,

Now we just refine and get,

Hope this helps.
r3t40
176 meters
Stefano is at +10 elevation while the hiker is at -166.4 elevation. The difference would be 10 - (-166.4) = 10 + 166.4 = 176.4 or approximately 176 meters