Hard Arithmetic Puzzles

#2732: 6 _ 3 _ 4 _ 8 = 16 hard #2734: 6 _ 3 _ 4 _ 9 = 17 hard #2738: 6 _ 3 _ 5 _ 5 = 17 hard #2742: 6 _ 3 _ 5 _ 2 = 20 hard #2749: 6 _ 3 _ 5 _ 7 = 17 hard #2751: 6 _ 3 _ 5 _ 8 = 18 hard #2753: 6 _ 3 _ 5 _ 9 = 19 hard #2759: 6 _ 3 _ 6 _ 6 = 19 hard #2761: 6 _ 3 _ 6 _ 6 = 17 hard #2764: 6 _ 3 _ 7 _ 7 = 19 hard #2765: 6 _ 3 _ 7 _ 9 = 14 hard #2767: 6 _ 3 _ 7 _ 3 = 17 hard #2769: 6 _ 3 _ 7 _ 4 = 18 hard #2771: 6 _ 3 _ 7 _ 5 = 19 hard #2773: 6 _ 3 _ 7 _ 6 = 20 hard #2778: 6 _ 3 _ 8 _ 4 = 16 hard #2779: 6 _ 3 _ 8 _ 8 = 17 hard #2780: 6 _ 3 _ 8 _ 9 = 16 hard #2782: 6 _ 3 _ 8 _ 1 = 15 hard #2783: 6 _ 3 _ 8 _ 3 = 19 hard #2789: 6 _ 3 _ 9 _ 9 = 19 hard #2790: 6 _ 3 _ 9 _ 9 = 17 hard #2799: 6 _ 3 _ 9 _ 7 = 14 hard #2801: 6 _ 3 _ 9 _ 8 = 16 hard #2802: 6 _ 3 _ 9 _ 9 = 11 hard #2803: 6 _ 3 _ 9 _ 9 = -7 hard #2808: 6 _ 4 _ 2 _ 7 = 20 hard #2824: 6 _ 4 _ 2 _ 9 = 12 hard #2838: 6 _ 4 _ 3 _ 7 = 15 hard #2839: 6 _ 4 _ 3 _ 8 = 16 hard #2841: 6 _ 4 _ 3 _ 9 = 17 hard #2855: 6 _ 4 _ 6 _ 9 = 12 hard #2858: 6 _ 4 _ 6 _ 8 = 18 hard #2859: 6 _ 4 _ 6 _ 9 = 16 hard #2862: 6 _ 4 _ 6 _ 5 = 20 hard #2871: 6 _ 4 _ 6 _ 7 = 16 hard #2873: 6 _ 4 _ 6 _ 8 = 17 hard #2875: 6 _ 4 _ 6 _ 9 = 18 hard #2878: 6 _ 4 _ 7 _ 2 = 20 hard #2894: 6 _ 4 _ 8 _ 9 = 12 hard #2896: 6 _ 4 _ 8 _ 1 = 13 hard #2899: 6 _ 4 _ 8 _ 4 = 16 hard #2901: 6 _ 4 _ 8 _ 5 = 17 hard #2904: 6 _ 4 _ 8 _ 7 = 19 hard #2906: 6 _ 4 _ 8 _ 8 = 20 hard #2908: 6 _ 4 _ 9 _ 6 = 12 hard #2910: 6 _ 4 _ 9 _ 6 = 16 hard #2915: 6 _ 5 _ 2 _ 3 = 20 hard