Answer:
-1
Explanation:
4u-5v=23
-2(2u+4v=16) We multiply by -2 here to destroy u's.
-4u-8v=16 we addition both processes
-13v=39 so, v=-3
4u-5(-3)=23, 4u=8 so, u=2
u+v= -3+2= -1
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