Answer:

Step-by-step explanation:
Consider the given differential equation is



Taking all variables on right sides.


Let as assume,
and 
Find partial derivatives
and 
and 
Since
, therefore the given differential equation is exact.
The solution of the exact differential equation is






X=3 because you subtract the three on both sides to get x alone. So you get: 7x=21 then you divide seven by 21 and get x=3
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