Question 935704
You must be missing some information.  The description gives one expression in three variables, and two equations in the same three variables.  You can eliminate any ONE variable using the two equations, and you will then have one equation in TWO variables and the same expression in THREE variables.  The expression has not yet a value.  To say you know the answer is 38 depends on information not given, and the information is needed before you can find the value.