Question

a)5a-4b=12
2a-4b=6

b) 2a-b=4
3a+2b=6

c) 3a-b=0
-4c+b= -2

d) x+y=35
4x+2y=102

e) x+y=200
5x+10y=1400

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Answer 1

Vamos là.

a)

5a - 4b = 12

2a - 4b = 6

5a - 2a = 12 - 6

3a = 6

a = 2

10 - 4b = 12

4b = -2

b = -1/2

b)

2a - b = 4

3a + 2b = 6

4a - 2b = 8

7a = 14

a = 2

4 - b = 4

b = 0

c)

3a - b = 0

-4a + b = -2

-a = -2

a = 2

b = 3a = 6

d)

x + y = 35

4x + 2y = 102

2x + 2y = 70

2x = 102 - 70 = 32

x = 16

16 + y = 35

y = 19

e)

x + y = 200

5x + 10y = 1400

x + 2y = 280

2y - y = 280 - 200 = 80

y = 80

x + 160 = 280

x = 280 - 160 = 120