Question 511320
GIVEN: ---: 3x-4y=17
       ---: y=x-5

 substitute Y into x-5 
---: 3x-4(4x-5)=17
---: 3x-4x+20=17
---: -x=17-20
---: -x=-3
multiply both side with -1
---: -1(-x=-3)-1
---: x=3 (ANSWER)
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then use the second given to find the answer for the Y
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y=3-5
y=-2 (ANSWER)