Easy
15
+3
HALVE
+11
÷2
−3
×2
−1
×7
+2
Medium
50
×3
×2/5
HALVE
−6
÷8
+5
×3/4
−1
×9
Hard
99
+1
×21/2
+2
÷6
−19
×4
−8
×25%
+19
There are two versions that can be printed, a default one, and one that requires less ink (no objectives or rules, and no lines).