Question 669722
Hint:


x- 9y =4


<font color="red">x</font> = <font color="blue">9y+4</font>


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2x +7y =8


2x +7y =8


2(<font color="red">x</font>) + 7y = 8


2(<font color="blue">9y+4</font>)+7y = 8


2(9y+4) + 7y = 8