8
Necunoscute... în ordine alfabetică:

a) [(a+138:6) x 9]: 6 = 50 × 2+ 8:4;
b) (bx9-78: 2) + 4 x 25 = 1 492;
C) [(c+540:6) x 7-100]: 20 = 30;
d) [(20+ 339:3+d:4)x7-5 x 400]: 3-22 x 3 +125 x 8 = 1000;
e) [416:8+ (128 x 5-124 x 3 - e)] x 100 - 23 x 13 = 5 301;
f) [(123: 3+ 362: 2) - 64 × 3+fx7=448:8 × 10;
g) 10 x {[(86 × 5+ 90: g) + 33 x 4] - 63 x 2} + 380: 2 = 4640;
h) 2 000 + {132 x 4-[(h:3-272) - 9 x 4] +263 x 12} = 5 680;
i) {[(563 x 12+ix 2): 4+328:8] x 4 - 136 x 13}:4-7735 = 496;
j) {896-[(j: 5+124 × 5 × 3:10-33): 5+ 364]}-200 × 2 × 2:8 = 365;
k) (45 363-[536 +9 x 43-(2k+6 x 8-5 x 2)]}- 1936:
4x8 = 40
622.
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