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Cat este ecuația (5x-1)x20=380

Răspuns :

( 5x - 1 ) × 20 = 380

5x = ( 380 : 20 ) + 1

5x = 19 + 1

5x = 20

x = 20 : 5

x = 4

(5x - 1)·20 = 380 <=> 5x - 1 = 380 : 20 <=> 5x - 1 = 19 <=> 5x = 19 + 1 <=> 5·x = 20 <=> x = 20 : 5 <=> x = 4