Question

a) 2x - 3y = 15
x - y = -3

b) x + y = 17
2x - 3y = 3

c) = 24 + 17
6x = 7y +24

d) x + y = 25
x - y = 13

Answer 1

A)
2x - 3y = 15
x - y = - 3     (-2)

  2x - 3y = 15
- 2x + 2y = 6  (+)
---------------------------
       - y = 21  (-1)
        y = - 21

x - y = - 3
x - (-21) = - 3
x + 21 = - 3
x = - 3 - 21
x = - 24

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b)
x + y = 17    (3)
2x - 3y = 3

3x + 3y = 51
2x - 3y = 3  (+)
------------------------
5x = 54
x = 54
     ------
        5

x + y = 17
 54  +  y =  17
------
  5

54 + 5y = 85
----------    ----
   5            5

5y = 85 - 54
5y = 31
y =  31
      ------
        5

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d)
x + y = 25
x - y = 13  (+)
-----------------
2x = 38
x = 38/2
x = 19

x - y = 13
19 - y = 13
19 - 13 = y
6 = y
y = 6

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