Question

Calcule o valor de b e c, onde b/4 = c/2 e b+c = 90. Marque a questão que corresponde aos valores de b e c.

Answer 1

{b + c = 90 ---------------> b = 90 - c    (I)
{b/4 = c/2 --->2b = 4c --> b = (4c)/2   (II)

(I) = (II)
90 - c = 4c/2 ---mmc=2
180 - 2c = 4c
180 = 6c ---> c = 180/6 ---> c = 30

(I) b = 90 -c --> b = 90 - 30 ---> b = 60

Verificando b/4 = c/2
60/4 = 15
30/2 = 15

Answer 2

Sendo:

$a/b=c/d$

Podemos dizer que:

$a/b=c/d=(a+c)/(b+d)$
__________________________

$b/4=c/2\\b/2=c/1\\b/2=c/1=(b+c)/(2+1)\\b/2=c/1=(b+c)/3\\b/2=c=90/3\\b/2=c=30$

$b/2=30\\b=2*30\\b=60\\\\c=30$