I don't think you can because the variables are different. You can only add the same variables.
The solution to these linear equations is (4,-3)
So the x-value is 4
:)))
Not funny ^ :|... The answer would be the Gupta Empire..
S is a subset of U, so all of the elements of S must be also elements of U
If U was {letters}, 4, 9, ? would not belong there
If U was {numbers }, x, y, ? would not belong to U
If U was {punctuation marks }, 4, 9, x, y would not be in U
all the elements of S are in U={ keys on a keyboard}
Answer: U={ keys on a keyboard}
