Question

valoarea lui A din egalitatea 100:5+{30:[(a-75:5)×6-7×4]}:15=21 este: URGENT!DAU COROANA!

Answer 1

100:5+{30:[(a-75:5)×6-7×4]}:15=21

20 + { 30 : [(a - 15) × 6 - 28]} : 15 = 21

{ 30 : [(a - 15) × 6 - 28]} : 15 = 21 - 20

{ 30 : [(a - 15) × 6 - 28]} : 15 = 1

30 : [(a - 15) × 6 - 28] = 1 × 15 = 15

(a - 15) × 6 - 28 = 30 : 15 = 2

(a - 15) × 6 = 2 + 28 = 30

a - 15 = 30 : 6

a - 15 = 5

a = 5 + 15

a = 20
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