1 2 2 1
13-7-4=6-4=2 13-(7-4)=13-3=10
(15-6)+8=9+8=17 15-(6+8)=15-14=1
11-6+5=5+5=10 11-(6+5)=11-11=0
1 2 2 1
13-7-4=6-4=2 13-(7-4)=13-3=10
1 2 2 1
(15-6)+8=9+8=17 15-(6+8)=15-14=1
1 2 2 1
11-6+5=5+5=10 11-(6+5)=11-11=0