HP 39gs Master Manual page 347

The function can also be used to solve problems with symbolic coefficients such as the one below.
LINSOLVE
Solve the system of equations:
The command is
LINSOLVE( 2.X+K.Y-1 AND (Q+3).X-Y-5, X AND Y)
and it produces the results shown.
Press to see the final solution in a
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scrollable format.
Note that "KY" above must be entered as K*Y using
variable. In the CAS variables can have more than one letter, as is discussed on page 328.
or the CAS will interpret KY as the name of a
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