I need help with #11 and #12 how do I do this?

  11. x = 6; y = 6.5

  12. x = 2; y = 4

Step-by-step explanation:

In each figure, the hash marks on the lines indicate the parallel lines (marked with red arrows) are equally-spaced. That means the two expressions involving x are equal to each other, and the two expressions involving y are equal to each other.

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11. 2x +1 = x +7

  x = 6 . . . . . . . subtract (x+1) from both sides

and

  3y -8 = y +5

  2y = 13 . . . . add (8-y) to both sides

  y = 6.5 . . . . divide by the coefficient of y

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12. x +3 = 3/2x +2

  1 = 1/2x . . . . . subtract (x+2)

  2 = x . . . . . . . multiply by 2

and

  2y -1 = 3y -5

  4 = y . . . . . . add (5 -2y)