Respuesta :

Assuming the question is -2×-9y=-25   -4×-9y=-23

Step 1: 
Make x the subject for both equations. 

-2× -9y = -25
-2× = -25 +9y
× = -25/-2 +9y/-2
x = 25/2 -9y/2

-4× -9y = -23
-4× = -23 +9y
× = -23/-4 +9y/-4
× = 23/4 -9y/4

Step 2:
Using simultaneous equations make the two equation equal each other

x = 25/2 -9y/2 = 50/4 -18y/4
× = 23/4 -9y/4
50/4 -18y/4 = 23/4 -9y/4

Step 3:
Solve for y 

50/4 -18y/4 = 23/4 -9y/4
50/4 -23/4 = -9y/4 +18y/4
27/4 = 9y/4 Multiply both sides by 4
27 = 9y
3 = y 

Step 4:
Sub y to determine x

-2× -9y = -25
-2× -9(3) = -25
-2× -27 = -25
-2× = -25 + 27
-2× = 2
x = 2/-2
x = -1

y = 3 & x = -1

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