Hard Arithmetic Puzzles

#2291: 5 _ 3 _ 9 _ 4 = 11 hard #2292: 5 _ 3 _ 9 _ 5 = 20 hard #2301: 5 _ 4 _ 2 _ 7 = 19 hard #2306: 5 _ 4 _ 2 _ 2 = 19 hard #2313: 5 _ 4 _ 2 _ 7 = 17 hard #2315: 5 _ 4 _ 2 _ 8 = 18 hard #2319: 5 _ 4 _ 2 _ 8 = 20 hard #2323: 5 _ 4 _ 3 _ 9 = 17 hard #2327: 5 _ 4 _ 3 _ 3 = 19 hard #2332: 5 _ 4 _ 4 _ 4 = 19 hard #2340: 5 _ 4 _ 6 _ 9 = 11 hard #2343: 5 _ 4 _ 6 _ 6 = 19 hard #2345: 5 _ 4 _ 7 _ 2 = 19 hard #2347: 5 _ 4 _ 7 _ 7 = 19 hard #2351: 5 _ 4 _ 8 _ 2 = 16 hard #2352: 5 _ 4 _ 8 _ 4 = 18 hard #2353: 5 _ 4 _ 8 _ 8 = 19 hard #2357: 5 _ 4 _ 8 _ 2 = 20 hard #2358: 5 _ 4 _ 8 _ 3 = 13 hard #2360: 5 _ 4 _ 8 _ 4 = 14 hard #2362: 5 _ 4 _ 8 _ 5 = 15 hard #2365: 5 _ 4 _ 8 _ 6 = 16 hard #2367: 5 _ 4 _ 8 _ 7 = 17 hard #2369: 5 _ 4 _ 8 _ 8 = 18 hard #2371: 5 _ 4 _ 9 _ 6 = 11 hard #2374: 5 _ 5 _ 2 _ 6 = 20 hard #2378: 5 _ 5 _ 2 _ 8 = 17 hard #2379: 5 _ 5 _ 2 _ 9 = 19 hard #2384: 5 _ 5 _ 3 _ 9 = 20 hard #2392: 5 _ 5 _ 4 _ 8 = 15 hard #2400: 5 _ 5 _ 6 _ 2 = 20 hard #2403: 5 _ 5 _ 8 _ 4 = 15 hard #2405: 5 _ 5 _ 8 _ 2 = 17 hard #2406: 5 _ 5 _ 9 _ 3 = 20 hard #2407: 5 _ 5 _ 9 _ 2 = 19 hard #2413: 5 _ 6 _ 2 _ 2 = 17 hard #2415: 5 _ 6 _ 2 _ 3 = 18 hard #2420: 5 _ 6 _ 2 _ 9 = 15 hard #2424: 5 _ 6 _ 3 _ 7 = 19 hard #2432: 5 _ 6 _ 3 _ 2 = 20 hard #2439: 5 _ 6 _ 3 _ 7 = 17 hard #2440: 5 _ 6 _ 3 _ 8 = 18 hard #2442: 5 _ 6 _ 3 _ 9 = 19 hard #2444: 5 _ 6 _ 3 _ 8 = 20 hard #2449: 5 _ 6 _ 4 _ 8 = 17 hard #2465: 5 _ 6 _ 6 _ 9 = 20 hard #2466: 5 _ 6 _ 7 _ 3 = 19 hard #2468: 5 _ 6 _ 8 _ 4 = 17 hard