Hard Arithmetic Puzzles

#3345: 7 _ 4 _ 7 _ 5 = 20 hard #3348: 7 _ 4 _ 8 _ 2 = -9 hard #3352: 7 _ 4 _ 8 _ 1 = 15 hard #3353: 7 _ 4 _ 8 _ 1 = 13 hard #3354: 7 _ 4 _ 8 _ 2 = 16 hard #3356: 7 _ 4 _ 8 _ 4 = 18 hard #3358: 7 _ 4 _ 8 _ 5 = 19 hard #3360: 7 _ 4 _ 8 _ 6 = 20 hard #3365: 7 _ 4 _ 9 _ 3 = 19 hard #3368: 7 _ 5 _ 2 _ 4 = 17 hard #3372: 7 _ 5 _ 3 _ 9 = -8 hard #3373: 7 _ 5 _ 4 _ 2 = 17 hard #3374: 7 _ 5 _ 4 _ 8 = 17 hard #3381: 7 _ 5 _ 7 _ 4 = 20 hard #3383: 7 _ 5 _ 8 _ 4 = 17 hard #3385: 7 _ 5 _ 9 _ 3 = -8 hard #3391: 7 _ 6 _ 2 _ 2 = 19 hard #3392: 7 _ 6 _ 2 _ 4 = 17 hard #3393: 7 _ 6 _ 2 _ 6 = 15 hard #3395: 7 _ 6 _ 2 _ 8 = 13 hard #3397: 7 _ 6 _ 3 _ 4 = 15 hard #3398: 7 _ 6 _ 3 _ 5 = 17 hard #3403: 7 _ 6 _ 3 _ 8 = -9 hard #3405: 7 _ 6 _ 3 _ 3 = 17 hard #3407: 7 _ 6 _ 3 _ 4 = 18 hard #3409: 7 _ 6 _ 3 _ 5 = 19 hard #3410: 7 _ 6 _ 3 _ 6 = 20 hard #3413: 7 _ 6 _ 4 _ 3 = 15 hard #3415: 7 _ 6 _ 4 _ 6 = 16 hard #3416: 7 _ 6 _ 4 _ 8 = 19 hard #3422: 7 _ 6 _ 5 _ 3 = 17 hard #3425: 7 _ 6 _ 6 _ 4 = 16 hard #3426: 7 _ 6 _ 6 _ 9 = 11 hard #3432: 7 _ 6 _ 7 _ 3 = 18 hard #3434: 7 _ 6 _ 8 _ 4 = 19 hard #3435: 7 _ 6 _ 8 _ 3 = -9 hard #3439: 7 _ 6 _ 9 _ 6 = 11 hard #3442: 7 _ 6 _ 9 _ 3 = 14 hard #3446: 7 _ 7 _ 2 _ 7 = 15 hard #3447: 7 _ 7 _ 2 _ 8 = 17 hard #3448: 7 _ 7 _ 2 _ 9 = 19 hard #3454: 7 _ 7 _ 3 _ 6 = 19 hard #3460: 7 _ 7 _ 4 _ 4 = 17 hard #3464: 7 _ 7 _ 6 _ 3 = 19 hard #3465: 7 _ 7 _ 7 _ 2 = 15 hard #3467: 7 _ 7 _ 8 _ 2 = 17 hard #3468: 7 _ 7 _ 9 _ 2 = 19 hard #3470: 7 _ 8 _ 2 _ 3 = 19 hard