Question

Me ajudem nesse sistema de equacoes {x+y=100 {7x+5y=620

Answer 1

x + y = 100 e 7x + 5y = 620

x + y = 100
x = 100 - y

7x + 5y = 620
7 (100 - y) + 5y = 620
700 - 7y + 5y = 620
700 -2y = 620
-2y = 620 - 700
-2y = -80
y = 80/2
y = 40

x = 100 - y
x = 100 - 40
x = 60

x = 60 e y = 40

Answer 2

x + y = 100        (-5)
7x + 5y= 620
-------------------
-5x - 5y= -500
7x +5y= 620
---------------------
2x= 120
 x= $\frac{120}{2}$
  x= 60

Agora iremos calcular o valor de Y:


7x + 5y= 620
420 + 5y= 620
5y= 620 -420
  5y= 200
    y= $\frac{200}{5}$
    y= 40