Question

Se știe că: a:b=3 b:2=c a-b=40. Află 3a-4b+5c

Answer 1

a:b=3 ; b:2=c ; a-b=40

<=> a = 3b   ; b = 2c

3a-4b+5c = 3x3b - 4x2c+5c = 3x3x2c-8c+5c = 18c-8c+5c = 15c

3b-b = 40 => 2b = 40 => b = 40:2 => b = 20

c = b:2 = 20:2 => c = 10  ; a = 3x20 => a = 60

3a-4b+5c = 15x10 = 150

Verificare: 3a-4b+5c = 3x60-4x20+5x10 = 180-80+50 = 150 , corect.