Maths question Please help

Question

Please help me :(

Solve the following pairs of simultaneous equations using the elimination method.
(a) x+ 2y = 12
-x + 3y = 8

(b) 14x – 5y = 12
-2x + 5y= 24

(c) x+y=6 -3x + 6y =0
(d) 7x – 4y = 23 2x – 2y = 4

Answer 1

a.     x + 2y = 12
     +   
       -x + 3y = 8    
        0 + 5y = 20 ---> y = 4
    x + 2*4 = 12 ---> x = 4
Answer:         (4, 4)

b.   14x - 5y = 12
   + 
      -2x + 5y = 24 
      12x + 0 = 36 ---> x = 3
    
14 * 3 - 5y = 12 ---> y = 6 
Answer:        (3, 6) 

c.      x + y = 6
     -3x + 6y = 0
Divide second equation by 3:
        x + y = 6
    +   
      -x + 2y = 0           0 + 3y = 6 ---> y = 2 
   x + 2 = 6 ---> x = 4 
Answer:       (4, 2) 

d.  7x - 4y = 23 
     2x - 2y = 4 ...... Multiply by (-2)
  
     7x - 4y = 23
  +  
    -4x + 4y = -8 
     3x + 0 = 15 ---> x = 5 
  7*5 - 4y = 23
    35 - 4y = 23 ---> y = 3 
Answer:      (5, 3)