Question

Me Ajudem , Nesses Sistemas :

1)X+Y=20
5X-3Y=60
----------------------------------

2)X+Y=100
3Y=5X-20

Answer 1

1) 
X+y= 20    y=20-x
5x-3y=60  

5x-3(20-x)=60 
5x-60+3x=60
8x=120
x=120/8
x= 15 

2) 

x+y=100         y=100-x
3y=5x-20
3(100-x)=5x-20
300-3x=5x-20
-3x-5x=-20-300
-8x=-320
x=320/-8
x=40

y=100-40
y=60
 
Espero ter ajudado !