Question

X Y
/ = /
7 2

Sabendo que: 3X+4y=87

Answer 1

Resposta:

x=  21

y = 6

S= { ( 21 , 6 )}

Explicação passo a passo:

$\dfrac{x}{7}=\dfrac{y}{2}\to2x=7y\\ \\ \\ \boxed{x=\dfrac{7y}{2}}$

Substituir x em :

$3x+4y=87\\ \\ 3.(\dfrac{7y}{2})+4y=87\\ \\ \\ \dfrac{21y}{2}+4y=87\\ \\ mmc=2\\ \\ 21y+8y=174\\ \\ 29y=174\\ \\ y=174:29\\ \\\boxed{ y=6}$

$Sendo:\\ \\ x=\dfrac{7y}{2}\\ \\ \\ x=\dfrac{7.(6)}{2}=\dfrac{42}{2}\\ \\ \\\boxed{ x=21}$