Arithmetic Operator Puzzles

#3505: 7 _ 8 _ 6 _ 4 = 19 hard #3506: 7 _ 8 _ 6 _ 3 = 11 medium #3507: 7 _ 8 _ 6 _ 9 = 19 hard #3508: 7 _ 8 _ 6 _ 3 = -9 hard #3509: 7 _ 8 _ 6 _ 4 = -5 medium #3510: 7 _ 8 _ 6 _ 3 = 3 easy #3511: 7 _ 8 _ 6 _ 9 = -5 medium #3512: 7 _ 8 _ 7 _ 4 = -7 medium #3513: 7 _ 8 _ 7 _ 2 = 16 hard #3514: 7 _ 8 _ 8 _ 4 = -9 hard #3515: 7 _ 8 _ 9 _ 6 = 19 hard #3516: 7 _ 8 _ 9 _ 6 = -5 medium #3517: 7 _ 9 _ 2 _ 3 = 13 hard #3518: 7 _ 9 _ 2 _ 3 = 1 easy #3519: 7 _ 9 _ 3 _ 2 = 13 hard #3520: 7 _ 9 _ 3 _ 4 = 19 hard #3521: 7 _ 9 _ 3 _ 2 = 1 easy #3522: 7 _ 9 _ 3 _ 4 = -5 medium #3523: 7 _ 9 _ 3 _ 5 = -8 hard #3524: 7 _ 9 _ 3 _ 2 = 19 hard #3525: 7 _ 9 _ 3 _ 3 = 18 hard #3526: 7 _ 9 _ 3 _ 5 = 16 hard #3527: 7 _ 9 _ 3 _ 6 = 15 hard #3528: 7 _ 9 _ 3 _ 7 = 14 hard #3529: 7 _ 9 _ 3 _ 8 = 13 hard #3530: 7 _ 9 _ 3 _ 9 = 12 hard #3531: 7 _ 9 _ 3 _ 6 = 14 hard #3532: 7 _ 9 _ 4 _ 3 = 19 hard #3533: 7 _ 9 _ 4 _ 6 = 13 hard #3534: 7 _ 9 _ 4 _ 3 = -5 medium #3535: 7 _ 9 _ 4 _ 6 = 1 easy #3536: 7 _ 9 _ 5 _ 3 = -8 hard #3537: 7 _ 9 _ 6 _ 4 = 13 hard #3538: 7 _ 9 _ 6 _ 8 = 19 hard #3539: 7 _ 9 _ 6 _ 4 = 1 easy #3540: 7 _ 9 _ 6 _ 8 = -5 medium #3541: 7 _ 9 _ 7 _ 2 = 18 hard #3542: 7 _ 9 _ 7 _ 3 = 3 easy #3543: 7 _ 9 _ 8 _ 6 = 19 hard #3544: 7 _ 9 _ 8 _ 6 = -5 medium #3545: 8 _ 1 _ 2 _ 8 = 4 easy #3546: 8 _ 1 _ 3 _ 9 = 11 hard #3547: 8 _ 1 _ 3 _ 9 = 5 easy #3548: 8 _ 1 _ 4 _ 8 = 6 easy #3549: 8 _ 2 _ 2 _ 4 = 9 medium #3550: 8 _ 2 _ 2 _ 4 = 7 easy #3551: 8 _ 2 _ 2 _ 2 = 17 hard #3552: 8 _ 2 _ 2 _ 2 = 15 hard