= (5 + 2) +
= 7
- 7 = ( 10 - 7) +
= 3
= 3,75
+10 = (4 + 10) +
= 14
- 12 = (12 - 12) +
= 
+ 3
= (4 + 3) + (
+
) = 7 
- 4
= (7 - 4) + (
-
) = 3
+ 5
= (3 + 5) + (
+
) = 8 
- 7
= (9 - 7) + (
+
) = 2
+ 2
= (4 + 2) + (
+
) = 6
= 7
+ 7
= (8 + 7) + (
+
) = 16