Answer :

naǫ
[tex]y=2x-5 \\ 4x-y=7 \\ \\ \hbox{substitute 2x-5 for y in the 2nd equation and solve for x:} \\ 4x-(2x-5)=7 \\ 4x-2x+5=7 \\ 2x+5=7 \\ 2x=7-5 \\ 2x=2 \\ x=\frac{2}{2} \\ x=1 \\ \\ \hbox{substitute 1 for x in the 1st equation:} \\ y=2 \times 1-5=2-5=-3 \\ \\ \hbox{the answer:} \\ x=1 \\ y=-3[/tex]
olemakpadu
This is straight forward:
You have already said:    y = 2x - 5 ...........(i)
                                             4x - y = 7............(ii)
So anywhere we see, y in equation (ii) we replace it with (2x - 5).
                                            4x - (2x - 5) = 7
                                             4x - 2x + 5  = 7
 Note minus sign before the bracket, changes sign inside the bracket.
                                              2x  + 5 = 7
                                              2x =  7 - 5.
                                              2x = 2        Divide both sides by 2.
                                                x  = 2/2
                                                x =1.
Remember from (i)  y = 2x - 5,  y = 2*1 - 5 = 2-5 = -3.
Therefore,  x = 1,    y = -3.
Those are the steps.

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