5+5-1=9 5+4-2=7 5+3-3=5 5+2-4=3
5+5=9,(-1) 5+4=7,(-2) 5+3=5,(-3) then 5+2=2,(-4)
5 + 5 = 9 5 + 4 = 7 5 + 3 = 5 5 + 2 = 3
5+5=10-1=9 5+4=9-2=7 5+3=8-3=5 5+2=7-4=3
5+5=10-1------->9, 5+4=9-2-------->7, 5+3=8-3-------->5 then
5+2=7-4---------->3
Answer is =3