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fie x supra3= cu y supra 4

Răspuns :

x/3 = y/4
3x + 4y = 75

x = 3y/4
3 × 3y/4 + 4y = 75
9y/4 + 16y/4 = 75 × 4/4
9y + 16y = 300
25y = 300
y = 12
x = 3×12/4 = 3×3 = 9