Hard Arithmetic Puzzles

#1331: 3 _ 6 _ 4 _ 9 = -7 hard #1332: 3 _ 6 _ 5 _ 2 = 18 hard #1335: 3 _ 6 _ 5 _ 5 = 17 hard #1338: 3 _ 6 _ 5 _ 8 = 20 hard #1341: 3 _ 6 _ 6 _ 3 = 20 hard #1342: 3 _ 6 _ 6 _ 6 = 19 hard #1345: 3 _ 6 _ 6 _ 6 = 17 hard #1346: 3 _ 6 _ 7 _ 3 = 17 hard #1347: 3 _ 6 _ 7 _ 7 = 19 hard #1348: 3 _ 6 _ 7 _ 7 = 17 hard #1349: 3 _ 6 _ 7 _ 9 = 14 hard #1352: 3 _ 6 _ 8 _ 3 = 19 hard #1353: 3 _ 6 _ 8 _ 4 = 15 hard #1354: 3 _ 6 _ 8 _ 4 = -9 hard #1355: 3 _ 6 _ 8 _ 4 = 20 hard #1356: 3 _ 6 _ 8 _ 8 = 19 hard #1357: 3 _ 6 _ 8 _ 2 = 14 hard #1358: 3 _ 6 _ 8 _ 8 = 17 hard #1359: 3 _ 6 _ 8 _ 9 = 16 hard #1367: 3 _ 6 _ 8 _ 5 = 20 hard #1373: 3 _ 6 _ 8 _ 9 = 13 hard #1377: 3 _ 6 _ 9 _ 9 = 19 hard #1378: 3 _ 6 _ 9 _ 9 = 17 hard #1391: 3 _ 6 _ 9 _ 7 = 14 hard #1393: 3 _ 6 _ 9 _ 8 = 16 hard #1394: 3 _ 6 _ 9 _ 9 = 11 hard #1395: 3 _ 6 _ 9 _ 9 = -7 hard #1397: 3 _ 6 _ 9 _ 4 = 18 hard #1398: 3 _ 7 _ 2 _ 4 = 17 hard #1399: 3 _ 7 _ 2 _ 2 = 20 hard #1401: 3 _ 7 _ 3 _ 6 = 17 hard #1402: 3 _ 7 _ 3 _ 3 = 20 hard #1405: 3 _ 7 _ 4 _ 2 = 17 hard #1406: 3 _ 7 _ 4 _ 4 = 20 hard #1408: 3 _ 7 _ 6 _ 3 = 17 hard #1409: 3 _ 7 _ 6 _ 6 = 20 hard #1410: 3 _ 7 _ 6 _ 9 = 14 hard #1412: 3 _ 7 _ 7 _ 7 = 20 hard #1413: 3 _ 7 _ 8 _ 2 = 17 hard #1414: 3 _ 7 _ 8 _ 4 = 19 hard #1415: 3 _ 7 _ 8 _ 8 = 20 hard #1416: 3 _ 7 _ 9 _ 3 = 18 hard #1417: 3 _ 7 _ 9 _ 9 = 20 hard #1418: 3 _ 7 _ 9 _ 6 = 14 hard #1421: 3 _ 8 _ 2 _ 3 = -9 hard #1425: 3 _ 8 _ 2 _ 2 = 14 hard #1430: 3 _ 8 _ 2 _ 6 = 18 hard #1434: 3 _ 8 _ 2 _ 8 = 20 hard