Given:

He does mistake in the order of giving preference.
We should give preference in the order, division, multiplication, addition, subtraction.
But, he gave the first preferrence to the subtraction.
72-8=64
Next, he used division
64/2=32
Next he adds 32 with 8.
So, he gets 50.
But the actual simplification is,
Simplifying we get,

Hence, the correct value of the expression is 86.
62 + x = 82
Subtract both sides by 62.
x = 20.
2x + 3y = 40
+
-2x + 2y = 20
___________ Adding both equations
0x + 5y = 60
____________
5y = 60
y = 60/5 = 12
y = 12.
Since we have gotten y =12, and the only option with that is option D.
So we don't have to solve for x.
<span>The answer is D.</span>