If 4x=8 (mod20) and 3x=16 (mod 20) then ....;

I am so sorry I dont have a real strategy for this.

lets guess and check:

So 12² = 144

144/20 is 

7 with a remainder of 4.

So the answer is 4.

deleted

Here’s a copy of the original question.

If \(4x\equiv 8\pmod{20}\) and \(3x\equiv 16\pmod{20}\), then what is the remainder when \(x^2\) is divided by 20?

GA