5x+4=y  y-3x=7   use substitution to solve the system of equation

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5x+4=y and y-3x=7.We can re-arrange the second formula to get x in terms of y, i.e y=7+3x.Then we can plug that y value into the first formula, so 5x+4=7+3xThen re-arranging5x-3x=7-42x=3x=1.5Then plug that x value in to work out y: 5(1.5)+4=y7.5+4=yy=11.5And then test the answer is correct: 11.5-3(1.5)=7Which is true, and 5(1.5)+4=11.5, which is trueso we have the correct x and y values.

5x + 4 = 3x + 75x = 3x + 32x =3x = 3/2