..........??????.........

Question

..........??????.........

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Answer 1

12-10=2;
10+7=17;
14-4=10;
17-7-3=7;
12+3+1=16;
9+1+5=15;
10+40+20=70;
90-40+10=60;
100-50-30=30.

Answer 2

12-10=2
10+7=17
14-4=10
17-7-3=7
12+3+1=16
9+1+5=15
10+40+20=70
90-40+10=60
100-50-30=20