Question

Solve the following pairs of equation by the substitution method
3x+4y=25
5x-6y=-9

Answer 1

(3x+4y=25) ====> 15x+20y=125 —(1)

(5x+4y=25) ====> 15x+12y=75 —(2)

Now :
(1)-(2)

(15x-15x) + (20y-12y) = 125-75
0+8y = 50
y = 25/4

3x+4y=25
3x + 4(25/4) = 25
3x = 0
x = 0
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Answer 2

15x+20y=125----1
15x-18y=-27----2
2-1
-38y=-152
y=4
substitution
3x+4*4=25
3x=25-16
3x=9
x=3