Question

Observe o exemplo para responder às questões:
a) x+y=20
x-y= 15

b) x+y=30
x-y=10

c) x+y=40
x-y=10

d) x+y=45
x-y=25

Answer 1

a) x+y=20
    x-y= 15
     2x = 35 ==> x= 35/2

y = 20 - x ==> y = 20 - 35/2 ==> y = (40-35)/2 ==> y = 5/2 
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b) x+y=30
    x-y=10
 2x = 40 ==> x= 20

y = 30 - x ==> y = 30 - 20 ==> y =  10  
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c) x+y=40
x-y=10
2x = 50 ==> x= 25

y = 40 - x ==> y = 40 - 25 ==> y =15  
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d) x+y=45
    x-y=25
  2x = 70 ==> x= 35

y = 45 - x ==> y = 45 - 35 ==> y =  10  
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